1  // SPDX-License-Identifier: GPL-2.0-only
2  /*
3   *  linux/mm/page_alloc.c
4   *
5   *  Manages the free list, the system allocates free pages here.
6   *  Note that kmalloc() lives in slab.c
7   *
8   *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
9   *  Swap reorganised 29.12.95, Stephen Tweedie
10   *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11   *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
12   *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
13   *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
14   *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
15   *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
16   */
17  
18  #include <linux/stddef.h>
19  #include <linux/mm.h>
20  #include <linux/highmem.h>
21  #include <linux/interrupt.h>
22  #include <linux/jiffies.h>
23  #include <linux/compiler.h>
24  #include <linux/kernel.h>
25  #include <linux/kasan.h>
26  #include <linux/kmsan.h>
27  #include <linux/module.h>
28  #include <linux/suspend.h>
29  #include <linux/ratelimit.h>
30  #include <linux/oom.h>
31  #include <linux/topology.h>
32  #include <linux/sysctl.h>
33  #include <linux/cpu.h>
34  #include <linux/cpuset.h>
35  #include <linux/pagevec.h>
36  #include <linux/memory_hotplug.h>
37  #include <linux/nodemask.h>
38  #include <linux/vmstat.h>
39  #include <linux/fault-inject.h>
40  #include <linux/compaction.h>
41  #include <trace/events/kmem.h>
42  #include <trace/events/oom.h>
43  #include <linux/prefetch.h>
44  #include <linux/mm_inline.h>
45  #include <linux/mmu_notifier.h>
46  #include <linux/migrate.h>
47  #include <linux/sched/mm.h>
48  #include <linux/page_owner.h>
49  #include <linux/page_table_check.h>
50  #include <linux/memcontrol.h>
51  #include <linux/ftrace.h>
52  #include <linux/lockdep.h>
53  #include <linux/psi.h>
54  #include <linux/khugepaged.h>
55  #include <linux/delayacct.h>
56  #include <linux/cacheinfo.h>
57  #include <linux/pgalloc_tag.h>
58  #include <asm/div64.h>
59  #include "internal.h"
60  #include "shuffle.h"
61  #include "page_reporting.h"
62  
63  /* Free Page Internal flags: for internal, non-pcp variants of free_pages(). */
64  typedef int __bitwise fpi_t;
65  
66  /* No special request */
67  #define FPI_NONE		((__force fpi_t)0)
68  
69  /*
70   * Skip free page reporting notification for the (possibly merged) page.
71   * This does not hinder free page reporting from grabbing the page,
72   * reporting it and marking it "reported" -  it only skips notifying
73   * the free page reporting infrastructure about a newly freed page. For
74   * example, used when temporarily pulling a page from a freelist and
75   * putting it back unmodified.
76   */
77  #define FPI_SKIP_REPORT_NOTIFY	((__force fpi_t)BIT(0))
78  
79  /*
80   * Place the (possibly merged) page to the tail of the freelist. Will ignore
81   * page shuffling (relevant code - e.g., memory onlining - is expected to
82   * shuffle the whole zone).
83   *
84   * Note: No code should rely on this flag for correctness - it's purely
85   *       to allow for optimizations when handing back either fresh pages
86   *       (memory onlining) or untouched pages (page isolation, free page
87   *       reporting).
88   */
89  #define FPI_TO_TAIL		((__force fpi_t)BIT(1))
90  
91  /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
92  static DEFINE_MUTEX(pcp_batch_high_lock);
93  #define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8)
94  
95  #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
96  /*
97   * On SMP, spin_trylock is sufficient protection.
98   * On PREEMPT_RT, spin_trylock is equivalent on both SMP and UP.
99   */
100  #define pcp_trylock_prepare(flags)	do { } while (0)
101  #define pcp_trylock_finish(flag)	do { } while (0)
102  #else
103  
104  /* UP spin_trylock always succeeds so disable IRQs to prevent re-entrancy. */
105  #define pcp_trylock_prepare(flags)	local_irq_save(flags)
106  #define pcp_trylock_finish(flags)	local_irq_restore(flags)
107  #endif
108  
109  /*
110   * Locking a pcp requires a PCP lookup followed by a spinlock. To avoid
111   * a migration causing the wrong PCP to be locked and remote memory being
112   * potentially allocated, pin the task to the CPU for the lookup+lock.
113   * preempt_disable is used on !RT because it is faster than migrate_disable.
114   * migrate_disable is used on RT because otherwise RT spinlock usage is
115   * interfered with and a high priority task cannot preempt the allocator.
116   */
117  #ifndef CONFIG_PREEMPT_RT
118  #define pcpu_task_pin()		preempt_disable()
119  #define pcpu_task_unpin()	preempt_enable()
120  #else
121  #define pcpu_task_pin()		migrate_disable()
122  #define pcpu_task_unpin()	migrate_enable()
123  #endif
124  
125  /*
126   * Generic helper to lookup and a per-cpu variable with an embedded spinlock.
127   * Return value should be used with equivalent unlock helper.
128   */
129  #define pcpu_spin_lock(type, member, ptr)				\
130  ({									\
131  	type *_ret;							\
132  	pcpu_task_pin();						\
133  	_ret = this_cpu_ptr(ptr);					\
134  	spin_lock(&_ret->member);					\
135  	_ret;								\
136  })
137  
138  #define pcpu_spin_trylock(type, member, ptr)				\
139  ({									\
140  	type *_ret;							\
141  	pcpu_task_pin();						\
142  	_ret = this_cpu_ptr(ptr);					\
143  	if (!spin_trylock(&_ret->member)) {				\
144  		pcpu_task_unpin();					\
145  		_ret = NULL;						\
146  	}								\
147  	_ret;								\
148  })
149  
150  #define pcpu_spin_unlock(member, ptr)					\
151  ({									\
152  	spin_unlock(&ptr->member);					\
153  	pcpu_task_unpin();						\
154  })
155  
156  /* struct per_cpu_pages specific helpers. */
157  #define pcp_spin_lock(ptr)						\
158  	pcpu_spin_lock(struct per_cpu_pages, lock, ptr)
159  
160  #define pcp_spin_trylock(ptr)						\
161  	pcpu_spin_trylock(struct per_cpu_pages, lock, ptr)
162  
163  #define pcp_spin_unlock(ptr)						\
164  	pcpu_spin_unlock(lock, ptr)
165  
166  #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
167  DEFINE_PER_CPU(int, numa_node);
168  EXPORT_PER_CPU_SYMBOL(numa_node);
169  #endif
170  
171  DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
172  
173  #ifdef CONFIG_HAVE_MEMORYLESS_NODES
174  /*
175   * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
176   * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
177   * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
178   * defined in <linux/topology.h>.
179   */
180  DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
181  EXPORT_PER_CPU_SYMBOL(_numa_mem_);
182  #endif
183  
184  static DEFINE_MUTEX(pcpu_drain_mutex);
185  
186  #ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
187  volatile unsigned long latent_entropy __latent_entropy;
188  EXPORT_SYMBOL(latent_entropy);
189  #endif
190  
191  /*
192   * Array of node states.
193   */
194  nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
195  	[N_POSSIBLE] = NODE_MASK_ALL,
196  	[N_ONLINE] = { { [0] = 1UL } },
197  #ifndef CONFIG_NUMA
198  	[N_NORMAL_MEMORY] = { { [0] = 1UL } },
199  #ifdef CONFIG_HIGHMEM
200  	[N_HIGH_MEMORY] = { { [0] = 1UL } },
201  #endif
202  	[N_MEMORY] = { { [0] = 1UL } },
203  	[N_CPU] = { { [0] = 1UL } },
204  #endif	/* NUMA */
205  };
206  EXPORT_SYMBOL(node_states);
207  
208  gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
209  
210  #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
211  unsigned int pageblock_order __read_mostly;
212  #endif
213  
214  static void __free_pages_ok(struct page *page, unsigned int order,
215  			    fpi_t fpi_flags);
216  
217  /*
218   * results with 256, 32 in the lowmem_reserve sysctl:
219   *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
220   *	1G machine -> (16M dma, 784M normal, 224M high)
221   *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
222   *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
223   *	HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
224   *
225   * TBD: should special case ZONE_DMA32 machines here - in those we normally
226   * don't need any ZONE_NORMAL reservation
227   */
228  static int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
229  #ifdef CONFIG_ZONE_DMA
230  	[ZONE_DMA] = 256,
231  #endif
232  #ifdef CONFIG_ZONE_DMA32
233  	[ZONE_DMA32] = 256,
234  #endif
235  	[ZONE_NORMAL] = 32,
236  #ifdef CONFIG_HIGHMEM
237  	[ZONE_HIGHMEM] = 0,
238  #endif
239  	[ZONE_MOVABLE] = 0,
240  };
241  
242  char * const zone_names[MAX_NR_ZONES] = {
243  #ifdef CONFIG_ZONE_DMA
244  	 "DMA",
245  #endif
246  #ifdef CONFIG_ZONE_DMA32
247  	 "DMA32",
248  #endif
249  	 "Normal",
250  #ifdef CONFIG_HIGHMEM
251  	 "HighMem",
252  #endif
253  	 "Movable",
254  #ifdef CONFIG_ZONE_DEVICE
255  	 "Device",
256  #endif
257  };
258  
259  const char * const migratetype_names[MIGRATE_TYPES] = {
260  	"Unmovable",
261  	"Movable",
262  	"Reclaimable",
263  	"HighAtomic",
264  #ifdef CONFIG_CMA
265  	"CMA",
266  #endif
267  #ifdef CONFIG_MEMORY_ISOLATION
268  	"Isolate",
269  #endif
270  };
271  
272  int min_free_kbytes = 1024;
273  int user_min_free_kbytes = -1;
274  static int watermark_boost_factor __read_mostly = 15000;
275  static int watermark_scale_factor = 10;
276  
277  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
278  int movable_zone;
279  EXPORT_SYMBOL(movable_zone);
280  
281  #if MAX_NUMNODES > 1
282  unsigned int nr_node_ids __read_mostly = MAX_NUMNODES;
283  unsigned int nr_online_nodes __read_mostly = 1;
284  EXPORT_SYMBOL(nr_node_ids);
285  EXPORT_SYMBOL(nr_online_nodes);
286  #endif
287  
288  static bool page_contains_unaccepted(struct page *page, unsigned int order);
289  static bool cond_accept_memory(struct zone *zone, unsigned int order);
290  static bool __free_unaccepted(struct page *page);
291  
292  int page_group_by_mobility_disabled __read_mostly;
293  
294  #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
295  /*
296   * During boot we initialize deferred pages on-demand, as needed, but once
297   * page_alloc_init_late() has finished, the deferred pages are all initialized,
298   * and we can permanently disable that path.
299   */
300  DEFINE_STATIC_KEY_TRUE(deferred_pages);
301  
deferred_pages_enabled(void)302  static inline bool deferred_pages_enabled(void)
303  {
304  	return static_branch_unlikely(&deferred_pages);
305  }
306  
307  /*
308   * deferred_grow_zone() is __init, but it is called from
309   * get_page_from_freelist() during early boot until deferred_pages permanently
310   * disables this call. This is why we have refdata wrapper to avoid warning,
311   * and to ensure that the function body gets unloaded.
312   */
313  static bool __ref
_deferred_grow_zone(struct zone * zone,unsigned int order)314  _deferred_grow_zone(struct zone *zone, unsigned int order)
315  {
316  	return deferred_grow_zone(zone, order);
317  }
318  #else
deferred_pages_enabled(void)319  static inline bool deferred_pages_enabled(void)
320  {
321  	return false;
322  }
323  
_deferred_grow_zone(struct zone * zone,unsigned int order)324  static inline bool _deferred_grow_zone(struct zone *zone, unsigned int order)
325  {
326  	return false;
327  }
328  #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
329  
330  /* Return a pointer to the bitmap storing bits affecting a block of pages */
get_pageblock_bitmap(const struct page * page,unsigned long pfn)331  static inline unsigned long *get_pageblock_bitmap(const struct page *page,
332  							unsigned long pfn)
333  {
334  #ifdef CONFIG_SPARSEMEM
335  	return section_to_usemap(__pfn_to_section(pfn));
336  #else
337  	return page_zone(page)->pageblock_flags;
338  #endif /* CONFIG_SPARSEMEM */
339  }
340  
pfn_to_bitidx(const struct page * page,unsigned long pfn)341  static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
342  {
343  #ifdef CONFIG_SPARSEMEM
344  	pfn &= (PAGES_PER_SECTION-1);
345  #else
346  	pfn = pfn - pageblock_start_pfn(page_zone(page)->zone_start_pfn);
347  #endif /* CONFIG_SPARSEMEM */
348  	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
349  }
350  
351  /**
352   * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
353   * @page: The page within the block of interest
354   * @pfn: The target page frame number
355   * @mask: mask of bits that the caller is interested in
356   *
357   * Return: pageblock_bits flags
358   */
get_pfnblock_flags_mask(const struct page * page,unsigned long pfn,unsigned long mask)359  unsigned long get_pfnblock_flags_mask(const struct page *page,
360  					unsigned long pfn, unsigned long mask)
361  {
362  	unsigned long *bitmap;
363  	unsigned long bitidx, word_bitidx;
364  	unsigned long word;
365  
366  	bitmap = get_pageblock_bitmap(page, pfn);
367  	bitidx = pfn_to_bitidx(page, pfn);
368  	word_bitidx = bitidx / BITS_PER_LONG;
369  	bitidx &= (BITS_PER_LONG-1);
370  	/*
371  	 * This races, without locks, with set_pfnblock_flags_mask(). Ensure
372  	 * a consistent read of the memory array, so that results, even though
373  	 * racy, are not corrupted.
374  	 */
375  	word = READ_ONCE(bitmap[word_bitidx]);
376  	return (word >> bitidx) & mask;
377  }
378  
get_pfnblock_migratetype(const struct page * page,unsigned long pfn)379  static __always_inline int get_pfnblock_migratetype(const struct page *page,
380  					unsigned long pfn)
381  {
382  	return get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
383  }
384  
385  /**
386   * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
387   * @page: The page within the block of interest
388   * @flags: The flags to set
389   * @pfn: The target page frame number
390   * @mask: mask of bits that the caller is interested in
391   */
set_pfnblock_flags_mask(struct page * page,unsigned long flags,unsigned long pfn,unsigned long mask)392  void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
393  					unsigned long pfn,
394  					unsigned long mask)
395  {
396  	unsigned long *bitmap;
397  	unsigned long bitidx, word_bitidx;
398  	unsigned long word;
399  
400  	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
401  	BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));
402  
403  	bitmap = get_pageblock_bitmap(page, pfn);
404  	bitidx = pfn_to_bitidx(page, pfn);
405  	word_bitidx = bitidx / BITS_PER_LONG;
406  	bitidx &= (BITS_PER_LONG-1);
407  
408  	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
409  
410  	mask <<= bitidx;
411  	flags <<= bitidx;
412  
413  	word = READ_ONCE(bitmap[word_bitidx]);
414  	do {
415  	} while (!try_cmpxchg(&bitmap[word_bitidx], &word, (word & ~mask) | flags));
416  }
417  
set_pageblock_migratetype(struct page * page,int migratetype)418  void set_pageblock_migratetype(struct page *page, int migratetype)
419  {
420  	if (unlikely(page_group_by_mobility_disabled &&
421  		     migratetype < MIGRATE_PCPTYPES))
422  		migratetype = MIGRATE_UNMOVABLE;
423  
424  	set_pfnblock_flags_mask(page, (unsigned long)migratetype,
425  				page_to_pfn(page), MIGRATETYPE_MASK);
426  }
427  
428  #ifdef CONFIG_DEBUG_VM
page_outside_zone_boundaries(struct zone * zone,struct page * page)429  static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
430  {
431  	int ret;
432  	unsigned seq;
433  	unsigned long pfn = page_to_pfn(page);
434  	unsigned long sp, start_pfn;
435  
436  	do {
437  		seq = zone_span_seqbegin(zone);
438  		start_pfn = zone->zone_start_pfn;
439  		sp = zone->spanned_pages;
440  		ret = !zone_spans_pfn(zone, pfn);
441  	} while (zone_span_seqretry(zone, seq));
442  
443  	if (ret)
444  		pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
445  			pfn, zone_to_nid(zone), zone->name,
446  			start_pfn, start_pfn + sp);
447  
448  	return ret;
449  }
450  
451  /*
452   * Temporary debugging check for pages not lying within a given zone.
453   */
bad_range(struct zone * zone,struct page * page)454  static bool __maybe_unused bad_range(struct zone *zone, struct page *page)
455  {
456  	if (page_outside_zone_boundaries(zone, page))
457  		return true;
458  	if (zone != page_zone(page))
459  		return true;
460  
461  	return false;
462  }
463  #else
bad_range(struct zone * zone,struct page * page)464  static inline bool __maybe_unused bad_range(struct zone *zone, struct page *page)
465  {
466  	return false;
467  }
468  #endif
469  
bad_page(struct page * page,const char * reason)470  static void bad_page(struct page *page, const char *reason)
471  {
472  	static unsigned long resume;
473  	static unsigned long nr_shown;
474  	static unsigned long nr_unshown;
475  
476  	/*
477  	 * Allow a burst of 60 reports, then keep quiet for that minute;
478  	 * or allow a steady drip of one report per second.
479  	 */
480  	if (nr_shown == 60) {
481  		if (time_before(jiffies, resume)) {
482  			nr_unshown++;
483  			goto out;
484  		}
485  		if (nr_unshown) {
486  			pr_alert(
487  			      "BUG: Bad page state: %lu messages suppressed\n",
488  				nr_unshown);
489  			nr_unshown = 0;
490  		}
491  		nr_shown = 0;
492  	}
493  	if (nr_shown++ == 0)
494  		resume = jiffies + 60 * HZ;
495  
496  	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
497  		current->comm, page_to_pfn(page));
498  	dump_page(page, reason);
499  
500  	print_modules();
501  	dump_stack();
502  out:
503  	/* Leave bad fields for debug, except PageBuddy could make trouble */
504  	if (PageBuddy(page))
505  		__ClearPageBuddy(page);
506  	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
507  }
508  
order_to_pindex(int migratetype,int order)509  static inline unsigned int order_to_pindex(int migratetype, int order)
510  {
511  	bool __maybe_unused movable;
512  
513  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
514  	if (order > PAGE_ALLOC_COSTLY_ORDER) {
515  		VM_BUG_ON(order != HPAGE_PMD_ORDER);
516  
517  		movable = migratetype == MIGRATE_MOVABLE;
518  
519  		return NR_LOWORDER_PCP_LISTS + movable;
520  	}
521  #else
522  	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
523  #endif
524  
525  	return (MIGRATE_PCPTYPES * order) + migratetype;
526  }
527  
pindex_to_order(unsigned int pindex)528  static inline int pindex_to_order(unsigned int pindex)
529  {
530  	int order = pindex / MIGRATE_PCPTYPES;
531  
532  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
533  	if (pindex >= NR_LOWORDER_PCP_LISTS)
534  		order = HPAGE_PMD_ORDER;
535  #else
536  	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
537  #endif
538  
539  	return order;
540  }
541  
pcp_allowed_order(unsigned int order)542  static inline bool pcp_allowed_order(unsigned int order)
543  {
544  	if (order <= PAGE_ALLOC_COSTLY_ORDER)
545  		return true;
546  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
547  	if (order == HPAGE_PMD_ORDER)
548  		return true;
549  #endif
550  	return false;
551  }
552  
553  /*
554   * Higher-order pages are called "compound pages".  They are structured thusly:
555   *
556   * The first PAGE_SIZE page is called the "head page" and have PG_head set.
557   *
558   * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
559   * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
560   *
561   * The first tail page's ->compound_order holds the order of allocation.
562   * This usage means that zero-order pages may not be compound.
563   */
564  
prep_compound_page(struct page * page,unsigned int order)565  void prep_compound_page(struct page *page, unsigned int order)
566  {
567  	int i;
568  	int nr_pages = 1 << order;
569  
570  	__SetPageHead(page);
571  	for (i = 1; i < nr_pages; i++)
572  		prep_compound_tail(page, i);
573  
574  	prep_compound_head(page, order);
575  }
576  
set_buddy_order(struct page * page,unsigned int order)577  static inline void set_buddy_order(struct page *page, unsigned int order)
578  {
579  	set_page_private(page, order);
580  	__SetPageBuddy(page);
581  }
582  
583  #ifdef CONFIG_COMPACTION
task_capc(struct zone * zone)584  static inline struct capture_control *task_capc(struct zone *zone)
585  {
586  	struct capture_control *capc = current->capture_control;
587  
588  	return unlikely(capc) &&
589  		!(current->flags & PF_KTHREAD) &&
590  		!capc->page &&
591  		capc->cc->zone == zone ? capc : NULL;
592  }
593  
594  static inline bool
compaction_capture(struct capture_control * capc,struct page * page,int order,int migratetype)595  compaction_capture(struct capture_control *capc, struct page *page,
596  		   int order, int migratetype)
597  {
598  	if (!capc || order != capc->cc->order)
599  		return false;
600  
601  	/* Do not accidentally pollute CMA or isolated regions*/
602  	if (is_migrate_cma(migratetype) ||
603  	    is_migrate_isolate(migratetype))
604  		return false;
605  
606  	/*
607  	 * Do not let lower order allocations pollute a movable pageblock
608  	 * unless compaction is also requesting movable pages.
609  	 * This might let an unmovable request use a reclaimable pageblock
610  	 * and vice-versa but no more than normal fallback logic which can
611  	 * have trouble finding a high-order free page.
612  	 */
613  	if (order < pageblock_order && migratetype == MIGRATE_MOVABLE &&
614  	    capc->cc->migratetype != MIGRATE_MOVABLE)
615  		return false;
616  
617  	capc->page = page;
618  	return true;
619  }
620  
621  #else
task_capc(struct zone * zone)622  static inline struct capture_control *task_capc(struct zone *zone)
623  {
624  	return NULL;
625  }
626  
627  static inline bool
compaction_capture(struct capture_control * capc,struct page * page,int order,int migratetype)628  compaction_capture(struct capture_control *capc, struct page *page,
629  		   int order, int migratetype)
630  {
631  	return false;
632  }
633  #endif /* CONFIG_COMPACTION */
634  
account_freepages(struct zone * zone,int nr_pages,int migratetype)635  static inline void account_freepages(struct zone *zone, int nr_pages,
636  				     int migratetype)
637  {
638  	lockdep_assert_held(&zone->lock);
639  
640  	if (is_migrate_isolate(migratetype))
641  		return;
642  
643  	__mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
644  
645  	if (is_migrate_cma(migratetype))
646  		__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, nr_pages);
647  	else if (is_migrate_highatomic(migratetype))
648  		WRITE_ONCE(zone->nr_free_highatomic,
649  			   zone->nr_free_highatomic + nr_pages);
650  }
651  
652  /* Used for pages not on another list */
__add_to_free_list(struct page * page,struct zone * zone,unsigned int order,int migratetype,bool tail)653  static inline void __add_to_free_list(struct page *page, struct zone *zone,
654  				      unsigned int order, int migratetype,
655  				      bool tail)
656  {
657  	struct free_area *area = &zone->free_area[order];
658  
659  	VM_WARN_ONCE(get_pageblock_migratetype(page) != migratetype,
660  		     "page type is %lu, passed migratetype is %d (nr=%d)\n",
661  		     get_pageblock_migratetype(page), migratetype, 1 << order);
662  
663  	if (tail)
664  		list_add_tail(&page->buddy_list, &area->free_list[migratetype]);
665  	else
666  		list_add(&page->buddy_list, &area->free_list[migratetype]);
667  	area->nr_free++;
668  }
669  
670  /*
671   * Used for pages which are on another list. Move the pages to the tail
672   * of the list - so the moved pages won't immediately be considered for
673   * allocation again (e.g., optimization for memory onlining).
674   */
move_to_free_list(struct page * page,struct zone * zone,unsigned int order,int old_mt,int new_mt)675  static inline void move_to_free_list(struct page *page, struct zone *zone,
676  				     unsigned int order, int old_mt, int new_mt)
677  {
678  	struct free_area *area = &zone->free_area[order];
679  
680  	/* Free page moving can fail, so it happens before the type update */
681  	VM_WARN_ONCE(get_pageblock_migratetype(page) != old_mt,
682  		     "page type is %lu, passed migratetype is %d (nr=%d)\n",
683  		     get_pageblock_migratetype(page), old_mt, 1 << order);
684  
685  	list_move_tail(&page->buddy_list, &area->free_list[new_mt]);
686  
687  	account_freepages(zone, -(1 << order), old_mt);
688  	account_freepages(zone, 1 << order, new_mt);
689  }
690  
__del_page_from_free_list(struct page * page,struct zone * zone,unsigned int order,int migratetype)691  static inline void __del_page_from_free_list(struct page *page, struct zone *zone,
692  					     unsigned int order, int migratetype)
693  {
694          VM_WARN_ONCE(get_pageblock_migratetype(page) != migratetype,
695  		     "page type is %lu, passed migratetype is %d (nr=%d)\n",
696  		     get_pageblock_migratetype(page), migratetype, 1 << order);
697  
698  	/* clear reported state and update reported page count */
699  	if (page_reported(page))
700  		__ClearPageReported(page);
701  
702  	list_del(&page->buddy_list);
703  	__ClearPageBuddy(page);
704  	set_page_private(page, 0);
705  	zone->free_area[order].nr_free--;
706  }
707  
del_page_from_free_list(struct page * page,struct zone * zone,unsigned int order,int migratetype)708  static inline void del_page_from_free_list(struct page *page, struct zone *zone,
709  					   unsigned int order, int migratetype)
710  {
711  	__del_page_from_free_list(page, zone, order, migratetype);
712  	account_freepages(zone, -(1 << order), migratetype);
713  }
714  
get_page_from_free_area(struct free_area * area,int migratetype)715  static inline struct page *get_page_from_free_area(struct free_area *area,
716  					    int migratetype)
717  {
718  	return list_first_entry_or_null(&area->free_list[migratetype],
719  					struct page, buddy_list);
720  }
721  
722  /*
723   * If this is less than the 2nd largest possible page, check if the buddy
724   * of the next-higher order is free. If it is, it's possible
725   * that pages are being freed that will coalesce soon. In case,
726   * that is happening, add the free page to the tail of the list
727   * so it's less likely to be used soon and more likely to be merged
728   * as a 2-level higher order page
729   */
730  static inline bool
buddy_merge_likely(unsigned long pfn,unsigned long buddy_pfn,struct page * page,unsigned int order)731  buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
732  		   struct page *page, unsigned int order)
733  {
734  	unsigned long higher_page_pfn;
735  	struct page *higher_page;
736  
737  	if (order >= MAX_PAGE_ORDER - 1)
738  		return false;
739  
740  	higher_page_pfn = buddy_pfn & pfn;
741  	higher_page = page + (higher_page_pfn - pfn);
742  
743  	return find_buddy_page_pfn(higher_page, higher_page_pfn, order + 1,
744  			NULL) != NULL;
745  }
746  
747  /*
748   * Freeing function for a buddy system allocator.
749   *
750   * The concept of a buddy system is to maintain direct-mapped table
751   * (containing bit values) for memory blocks of various "orders".
752   * The bottom level table contains the map for the smallest allocatable
753   * units of memory (here, pages), and each level above it describes
754   * pairs of units from the levels below, hence, "buddies".
755   * At a high level, all that happens here is marking the table entry
756   * at the bottom level available, and propagating the changes upward
757   * as necessary, plus some accounting needed to play nicely with other
758   * parts of the VM system.
759   * At each level, we keep a list of pages, which are heads of continuous
760   * free pages of length of (1 << order) and marked with PageBuddy.
761   * Page's order is recorded in page_private(page) field.
762   * So when we are allocating or freeing one, we can derive the state of the
763   * other.  That is, if we allocate a small block, and both were
764   * free, the remainder of the region must be split into blocks.
765   * If a block is freed, and its buddy is also free, then this
766   * triggers coalescing into a block of larger size.
767   *
768   * -- nyc
769   */
770  
__free_one_page(struct page * page,unsigned long pfn,struct zone * zone,unsigned int order,int migratetype,fpi_t fpi_flags)771  static inline void __free_one_page(struct page *page,
772  		unsigned long pfn,
773  		struct zone *zone, unsigned int order,
774  		int migratetype, fpi_t fpi_flags)
775  {
776  	struct capture_control *capc = task_capc(zone);
777  	unsigned long buddy_pfn = 0;
778  	unsigned long combined_pfn;
779  	struct page *buddy;
780  	bool to_tail;
781  
782  	VM_BUG_ON(!zone_is_initialized(zone));
783  	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
784  
785  	VM_BUG_ON(migratetype == -1);
786  	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
787  	VM_BUG_ON_PAGE(bad_range(zone, page), page);
788  
789  	account_freepages(zone, 1 << order, migratetype);
790  
791  	while (order < MAX_PAGE_ORDER) {
792  		int buddy_mt = migratetype;
793  
794  		if (compaction_capture(capc, page, order, migratetype)) {
795  			account_freepages(zone, -(1 << order), migratetype);
796  			return;
797  		}
798  
799  		buddy = find_buddy_page_pfn(page, pfn, order, &buddy_pfn);
800  		if (!buddy)
801  			goto done_merging;
802  
803  		if (unlikely(order >= pageblock_order)) {
804  			/*
805  			 * We want to prevent merge between freepages on pageblock
806  			 * without fallbacks and normal pageblock. Without this,
807  			 * pageblock isolation could cause incorrect freepage or CMA
808  			 * accounting or HIGHATOMIC accounting.
809  			 */
810  			buddy_mt = get_pfnblock_migratetype(buddy, buddy_pfn);
811  
812  			if (migratetype != buddy_mt &&
813  			    (!migratetype_is_mergeable(migratetype) ||
814  			     !migratetype_is_mergeable(buddy_mt)))
815  				goto done_merging;
816  		}
817  
818  		/*
819  		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
820  		 * merge with it and move up one order.
821  		 */
822  		if (page_is_guard(buddy))
823  			clear_page_guard(zone, buddy, order);
824  		else
825  			__del_page_from_free_list(buddy, zone, order, buddy_mt);
826  
827  		if (unlikely(buddy_mt != migratetype)) {
828  			/*
829  			 * Match buddy type. This ensures that an
830  			 * expand() down the line puts the sub-blocks
831  			 * on the right freelists.
832  			 */
833  			set_pageblock_migratetype(buddy, migratetype);
834  		}
835  
836  		combined_pfn = buddy_pfn & pfn;
837  		page = page + (combined_pfn - pfn);
838  		pfn = combined_pfn;
839  		order++;
840  	}
841  
842  done_merging:
843  	set_buddy_order(page, order);
844  
845  	if (fpi_flags & FPI_TO_TAIL)
846  		to_tail = true;
847  	else if (is_shuffle_order(order))
848  		to_tail = shuffle_pick_tail();
849  	else
850  		to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
851  
852  	__add_to_free_list(page, zone, order, migratetype, to_tail);
853  
854  	/* Notify page reporting subsystem of freed page */
855  	if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
856  		page_reporting_notify_free(order);
857  }
858  
859  /*
860   * A bad page could be due to a number of fields. Instead of multiple branches,
861   * try and check multiple fields with one check. The caller must do a detailed
862   * check if necessary.
863   */
page_expected_state(struct page * page,unsigned long check_flags)864  static inline bool page_expected_state(struct page *page,
865  					unsigned long check_flags)
866  {
867  	if (unlikely(atomic_read(&page->_mapcount) != -1))
868  		return false;
869  
870  	if (unlikely((unsigned long)page->mapping |
871  			page_ref_count(page) |
872  #ifdef CONFIG_MEMCG
873  			page->memcg_data |
874  #endif
875  #ifdef CONFIG_PAGE_POOL
876  			((page->pp_magic & ~0x3UL) == PP_SIGNATURE) |
877  #endif
878  			(page->flags & check_flags)))
879  		return false;
880  
881  	return true;
882  }
883  
page_bad_reason(struct page * page,unsigned long flags)884  static const char *page_bad_reason(struct page *page, unsigned long flags)
885  {
886  	const char *bad_reason = NULL;
887  
888  	if (unlikely(atomic_read(&page->_mapcount) != -1))
889  		bad_reason = "nonzero mapcount";
890  	if (unlikely(page->mapping != NULL))
891  		bad_reason = "non-NULL mapping";
892  	if (unlikely(page_ref_count(page) != 0))
893  		bad_reason = "nonzero _refcount";
894  	if (unlikely(page->flags & flags)) {
895  		if (flags == PAGE_FLAGS_CHECK_AT_PREP)
896  			bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
897  		else
898  			bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
899  	}
900  #ifdef CONFIG_MEMCG
901  	if (unlikely(page->memcg_data))
902  		bad_reason = "page still charged to cgroup";
903  #endif
904  #ifdef CONFIG_PAGE_POOL
905  	if (unlikely((page->pp_magic & ~0x3UL) == PP_SIGNATURE))
906  		bad_reason = "page_pool leak";
907  #endif
908  	return bad_reason;
909  }
910  
free_page_is_bad_report(struct page * page)911  static void free_page_is_bad_report(struct page *page)
912  {
913  	bad_page(page,
914  		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
915  }
916  
free_page_is_bad(struct page * page)917  static inline bool free_page_is_bad(struct page *page)
918  {
919  	if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
920  		return false;
921  
922  	/* Something has gone sideways, find it */
923  	free_page_is_bad_report(page);
924  	return true;
925  }
926  
is_check_pages_enabled(void)927  static inline bool is_check_pages_enabled(void)
928  {
929  	return static_branch_unlikely(&check_pages_enabled);
930  }
931  
free_tail_page_prepare(struct page * head_page,struct page * page)932  static int free_tail_page_prepare(struct page *head_page, struct page *page)
933  {
934  	struct folio *folio = (struct folio *)head_page;
935  	int ret = 1;
936  
937  	/*
938  	 * We rely page->lru.next never has bit 0 set, unless the page
939  	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
940  	 */
941  	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
942  
943  	if (!is_check_pages_enabled()) {
944  		ret = 0;
945  		goto out;
946  	}
947  	switch (page - head_page) {
948  	case 1:
949  		/* the first tail page: these may be in place of ->mapping */
950  		if (unlikely(folio_entire_mapcount(folio))) {
951  			bad_page(page, "nonzero entire_mapcount");
952  			goto out;
953  		}
954  		if (unlikely(folio_large_mapcount(folio))) {
955  			bad_page(page, "nonzero large_mapcount");
956  			goto out;
957  		}
958  		if (unlikely(atomic_read(&folio->_nr_pages_mapped))) {
959  			bad_page(page, "nonzero nr_pages_mapped");
960  			goto out;
961  		}
962  		if (unlikely(atomic_read(&folio->_pincount))) {
963  			bad_page(page, "nonzero pincount");
964  			goto out;
965  		}
966  		break;
967  	case 2:
968  		/* the second tail page: deferred_list overlaps ->mapping */
969  		if (unlikely(!list_empty(&folio->_deferred_list))) {
970  			bad_page(page, "on deferred list");
971  			goto out;
972  		}
973  		break;
974  	default:
975  		if (page->mapping != TAIL_MAPPING) {
976  			bad_page(page, "corrupted mapping in tail page");
977  			goto out;
978  		}
979  		break;
980  	}
981  	if (unlikely(!PageTail(page))) {
982  		bad_page(page, "PageTail not set");
983  		goto out;
984  	}
985  	if (unlikely(compound_head(page) != head_page)) {
986  		bad_page(page, "compound_head not consistent");
987  		goto out;
988  	}
989  	ret = 0;
990  out:
991  	page->mapping = NULL;
992  	clear_compound_head(page);
993  	return ret;
994  }
995  
996  /*
997   * Skip KASAN memory poisoning when either:
998   *
999   * 1. For generic KASAN: deferred memory initialization has not yet completed.
1000   *    Tag-based KASAN modes skip pages freed via deferred memory initialization
1001   *    using page tags instead (see below).
1002   * 2. For tag-based KASAN modes: the page has a match-all KASAN tag, indicating
1003   *    that error detection is disabled for accesses via the page address.
1004   *
1005   * Pages will have match-all tags in the following circumstances:
1006   *
1007   * 1. Pages are being initialized for the first time, including during deferred
1008   *    memory init; see the call to page_kasan_tag_reset in __init_single_page.
1009   * 2. The allocation was not unpoisoned due to __GFP_SKIP_KASAN, with the
1010   *    exception of pages unpoisoned by kasan_unpoison_vmalloc.
1011   * 3. The allocation was excluded from being checked due to sampling,
1012   *    see the call to kasan_unpoison_pages.
1013   *
1014   * Poisoning pages during deferred memory init will greatly lengthen the
1015   * process and cause problem in large memory systems as the deferred pages
1016   * initialization is done with interrupt disabled.
1017   *
1018   * Assuming that there will be no reference to those newly initialized
1019   * pages before they are ever allocated, this should have no effect on
1020   * KASAN memory tracking as the poison will be properly inserted at page
1021   * allocation time. The only corner case is when pages are allocated by
1022   * on-demand allocation and then freed again before the deferred pages
1023   * initialization is done, but this is not likely to happen.
1024   */
should_skip_kasan_poison(struct page * page)1025  static inline bool should_skip_kasan_poison(struct page *page)
1026  {
1027  	if (IS_ENABLED(CONFIG_KASAN_GENERIC))
1028  		return deferred_pages_enabled();
1029  
1030  	return page_kasan_tag(page) == KASAN_TAG_KERNEL;
1031  }
1032  
kernel_init_pages(struct page * page,int numpages)1033  static void kernel_init_pages(struct page *page, int numpages)
1034  {
1035  	int i;
1036  
1037  	/* s390's use of memset() could override KASAN redzones. */
1038  	kasan_disable_current();
1039  	for (i = 0; i < numpages; i++)
1040  		clear_highpage_kasan_tagged(page + i);
1041  	kasan_enable_current();
1042  }
1043  
free_pages_prepare(struct page * page,unsigned int order)1044  __always_inline bool free_pages_prepare(struct page *page,
1045  			unsigned int order)
1046  {
1047  	int bad = 0;
1048  	bool skip_kasan_poison = should_skip_kasan_poison(page);
1049  	bool init = want_init_on_free();
1050  	bool compound = PageCompound(page);
1051  	struct folio *folio = page_folio(page);
1052  
1053  	VM_BUG_ON_PAGE(PageTail(page), page);
1054  
1055  	trace_mm_page_free(page, order);
1056  	kmsan_free_page(page, order);
1057  
1058  	if (memcg_kmem_online() && PageMemcgKmem(page))
1059  		__memcg_kmem_uncharge_page(page, order);
1060  
1061  	/*
1062  	 * In rare cases, when truncation or holepunching raced with
1063  	 * munlock after VM_LOCKED was cleared, Mlocked may still be
1064  	 * found set here.  This does not indicate a problem, unless
1065  	 * "unevictable_pgs_cleared" appears worryingly large.
1066  	 */
1067  	if (unlikely(folio_test_mlocked(folio))) {
1068  		long nr_pages = folio_nr_pages(folio);
1069  
1070  		__folio_clear_mlocked(folio);
1071  		zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
1072  		count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
1073  	}
1074  
1075  	if (unlikely(PageHWPoison(page)) && !order) {
1076  		/* Do not let hwpoison pages hit pcplists/buddy */
1077  		reset_page_owner(page, order);
1078  		page_table_check_free(page, order);
1079  		pgalloc_tag_sub(page, 1 << order);
1080  
1081  		/*
1082  		 * The page is isolated and accounted for.
1083  		 * Mark the codetag as empty to avoid accounting error
1084  		 * when the page is freed by unpoison_memory().
1085  		 */
1086  		clear_page_tag_ref(page);
1087  		return false;
1088  	}
1089  
1090  	VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
1091  
1092  	/*
1093  	 * Check tail pages before head page information is cleared to
1094  	 * avoid checking PageCompound for order-0 pages.
1095  	 */
1096  	if (unlikely(order)) {
1097  		int i;
1098  
1099  		if (compound)
1100  			page[1].flags &= ~PAGE_FLAGS_SECOND;
1101  		for (i = 1; i < (1 << order); i++) {
1102  			if (compound)
1103  				bad += free_tail_page_prepare(page, page + i);
1104  			if (is_check_pages_enabled()) {
1105  				if (free_page_is_bad(page + i)) {
1106  					bad++;
1107  					continue;
1108  				}
1109  			}
1110  			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1111  		}
1112  	}
1113  	if (PageMappingFlags(page)) {
1114  		if (PageAnon(page))
1115  			mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
1116  		page->mapping = NULL;
1117  	}
1118  	if (is_check_pages_enabled()) {
1119  		if (free_page_is_bad(page))
1120  			bad++;
1121  		if (bad)
1122  			return false;
1123  	}
1124  
1125  	page_cpupid_reset_last(page);
1126  	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1127  	reset_page_owner(page, order);
1128  	page_table_check_free(page, order);
1129  	pgalloc_tag_sub(page, 1 << order);
1130  
1131  	if (!PageHighMem(page)) {
1132  		debug_check_no_locks_freed(page_address(page),
1133  					   PAGE_SIZE << order);
1134  		debug_check_no_obj_freed(page_address(page),
1135  					   PAGE_SIZE << order);
1136  	}
1137  
1138  	kernel_poison_pages(page, 1 << order);
1139  
1140  	/*
1141  	 * As memory initialization might be integrated into KASAN,
1142  	 * KASAN poisoning and memory initialization code must be
1143  	 * kept together to avoid discrepancies in behavior.
1144  	 *
1145  	 * With hardware tag-based KASAN, memory tags must be set before the
1146  	 * page becomes unavailable via debug_pagealloc or arch_free_page.
1147  	 */
1148  	if (!skip_kasan_poison) {
1149  		kasan_poison_pages(page, order, init);
1150  
1151  		/* Memory is already initialized if KASAN did it internally. */
1152  		if (kasan_has_integrated_init())
1153  			init = false;
1154  	}
1155  	if (init)
1156  		kernel_init_pages(page, 1 << order);
1157  
1158  	/*
1159  	 * arch_free_page() can make the page's contents inaccessible.  s390
1160  	 * does this.  So nothing which can access the page's contents should
1161  	 * happen after this.
1162  	 */
1163  	arch_free_page(page, order);
1164  
1165  	debug_pagealloc_unmap_pages(page, 1 << order);
1166  
1167  	return true;
1168  }
1169  
1170  /*
1171   * Frees a number of pages from the PCP lists
1172   * Assumes all pages on list are in same zone.
1173   * count is the number of pages to free.
1174   */
free_pcppages_bulk(struct zone * zone,int count,struct per_cpu_pages * pcp,int pindex)1175  static void free_pcppages_bulk(struct zone *zone, int count,
1176  					struct per_cpu_pages *pcp,
1177  					int pindex)
1178  {
1179  	unsigned long flags;
1180  	unsigned int order;
1181  	struct page *page;
1182  
1183  	/*
1184  	 * Ensure proper count is passed which otherwise would stuck in the
1185  	 * below while (list_empty(list)) loop.
1186  	 */
1187  	count = min(pcp->count, count);
1188  
1189  	/* Ensure requested pindex is drained first. */
1190  	pindex = pindex - 1;
1191  
1192  	spin_lock_irqsave(&zone->lock, flags);
1193  
1194  	while (count > 0) {
1195  		struct list_head *list;
1196  		int nr_pages;
1197  
1198  		/* Remove pages from lists in a round-robin fashion. */
1199  		do {
1200  			if (++pindex > NR_PCP_LISTS - 1)
1201  				pindex = 0;
1202  			list = &pcp->lists[pindex];
1203  		} while (list_empty(list));
1204  
1205  		order = pindex_to_order(pindex);
1206  		nr_pages = 1 << order;
1207  		do {
1208  			unsigned long pfn;
1209  			int mt;
1210  
1211  			page = list_last_entry(list, struct page, pcp_list);
1212  			pfn = page_to_pfn(page);
1213  			mt = get_pfnblock_migratetype(page, pfn);
1214  
1215  			/* must delete to avoid corrupting pcp list */
1216  			list_del(&page->pcp_list);
1217  			count -= nr_pages;
1218  			pcp->count -= nr_pages;
1219  
1220  			__free_one_page(page, pfn, zone, order, mt, FPI_NONE);
1221  			trace_mm_page_pcpu_drain(page, order, mt);
1222  		} while (count > 0 && !list_empty(list));
1223  	}
1224  
1225  	spin_unlock_irqrestore(&zone->lock, flags);
1226  }
1227  
1228  /* Split a multi-block free page into its individual pageblocks. */
split_large_buddy(struct zone * zone,struct page * page,unsigned long pfn,int order,fpi_t fpi)1229  static void split_large_buddy(struct zone *zone, struct page *page,
1230  			      unsigned long pfn, int order, fpi_t fpi)
1231  {
1232  	unsigned long end = pfn + (1 << order);
1233  
1234  	VM_WARN_ON_ONCE(!IS_ALIGNED(pfn, 1 << order));
1235  	/* Caller removed page from freelist, buddy info cleared! */
1236  	VM_WARN_ON_ONCE(PageBuddy(page));
1237  
1238  	if (order > pageblock_order)
1239  		order = pageblock_order;
1240  
1241  	while (pfn != end) {
1242  		int mt = get_pfnblock_migratetype(page, pfn);
1243  
1244  		__free_one_page(page, pfn, zone, order, mt, fpi);
1245  		pfn += 1 << order;
1246  		page = pfn_to_page(pfn);
1247  	}
1248  }
1249  
free_one_page(struct zone * zone,struct page * page,unsigned long pfn,unsigned int order,fpi_t fpi_flags)1250  static void free_one_page(struct zone *zone, struct page *page,
1251  			  unsigned long pfn, unsigned int order,
1252  			  fpi_t fpi_flags)
1253  {
1254  	unsigned long flags;
1255  
1256  	spin_lock_irqsave(&zone->lock, flags);
1257  	split_large_buddy(zone, page, pfn, order, fpi_flags);
1258  	spin_unlock_irqrestore(&zone->lock, flags);
1259  
1260  	__count_vm_events(PGFREE, 1 << order);
1261  }
1262  
__free_pages_ok(struct page * page,unsigned int order,fpi_t fpi_flags)1263  static void __free_pages_ok(struct page *page, unsigned int order,
1264  			    fpi_t fpi_flags)
1265  {
1266  	unsigned long pfn = page_to_pfn(page);
1267  	struct zone *zone = page_zone(page);
1268  
1269  	if (free_pages_prepare(page, order))
1270  		free_one_page(zone, page, pfn, order, fpi_flags);
1271  }
1272  
__free_pages_core(struct page * page,unsigned int order,enum meminit_context context)1273  void __meminit __free_pages_core(struct page *page, unsigned int order,
1274  		enum meminit_context context)
1275  {
1276  	unsigned int nr_pages = 1 << order;
1277  	struct page *p = page;
1278  	unsigned int loop;
1279  
1280  	/*
1281  	 * When initializing the memmap, __init_single_page() sets the refcount
1282  	 * of all pages to 1 ("allocated"/"not free"). We have to set the
1283  	 * refcount of all involved pages to 0.
1284  	 *
1285  	 * Note that hotplugged memory pages are initialized to PageOffline().
1286  	 * Pages freed from memblock might be marked as reserved.
1287  	 */
1288  	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) &&
1289  	    unlikely(context == MEMINIT_HOTPLUG)) {
1290  		for (loop = 0; loop < nr_pages; loop++, p++) {
1291  			VM_WARN_ON_ONCE(PageReserved(p));
1292  			__ClearPageOffline(p);
1293  			set_page_count(p, 0);
1294  		}
1295  
1296  		/*
1297  		 * Freeing the page with debug_pagealloc enabled will try to
1298  		 * unmap it; some archs don't like double-unmappings, so
1299  		 * map it first.
1300  		 */
1301  		debug_pagealloc_map_pages(page, nr_pages);
1302  		adjust_managed_page_count(page, nr_pages);
1303  	} else {
1304  		for (loop = 0; loop < nr_pages; loop++, p++) {
1305  			__ClearPageReserved(p);
1306  			set_page_count(p, 0);
1307  		}
1308  
1309  		/* memblock adjusts totalram_pages() manually. */
1310  		atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
1311  	}
1312  
1313  	if (page_contains_unaccepted(page, order)) {
1314  		if (order == MAX_PAGE_ORDER && __free_unaccepted(page))
1315  			return;
1316  
1317  		accept_memory(page_to_phys(page), PAGE_SIZE << order);
1318  	}
1319  
1320  	/*
1321  	 * Bypass PCP and place fresh pages right to the tail, primarily
1322  	 * relevant for memory onlining.
1323  	 */
1324  	__free_pages_ok(page, order, FPI_TO_TAIL);
1325  }
1326  
1327  /*
1328   * Check that the whole (or subset of) a pageblock given by the interval of
1329   * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
1330   * with the migration of free compaction scanner.
1331   *
1332   * Return struct page pointer of start_pfn, or NULL if checks were not passed.
1333   *
1334   * It's possible on some configurations to have a setup like node0 node1 node0
1335   * i.e. it's possible that all pages within a zones range of pages do not
1336   * belong to a single zone. We assume that a border between node0 and node1
1337   * can occur within a single pageblock, but not a node0 node1 node0
1338   * interleaving within a single pageblock. It is therefore sufficient to check
1339   * the first and last page of a pageblock and avoid checking each individual
1340   * page in a pageblock.
1341   *
1342   * Note: the function may return non-NULL struct page even for a page block
1343   * which contains a memory hole (i.e. there is no physical memory for a subset
1344   * of the pfn range). For example, if the pageblock order is MAX_PAGE_ORDER, which
1345   * will fall into 2 sub-sections, and the end pfn of the pageblock may be hole
1346   * even though the start pfn is online and valid. This should be safe most of
1347   * the time because struct pages are still initialized via init_unavailable_range()
1348   * and pfn walkers shouldn't touch any physical memory range for which they do
1349   * not recognize any specific metadata in struct pages.
1350   */
__pageblock_pfn_to_page(unsigned long start_pfn,unsigned long end_pfn,struct zone * zone)1351  struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
1352  				     unsigned long end_pfn, struct zone *zone)
1353  {
1354  	struct page *start_page;
1355  	struct page *end_page;
1356  
1357  	/* end_pfn is one past the range we are checking */
1358  	end_pfn--;
1359  
1360  	if (!pfn_valid(end_pfn))
1361  		return NULL;
1362  
1363  	start_page = pfn_to_online_page(start_pfn);
1364  	if (!start_page)
1365  		return NULL;
1366  
1367  	if (page_zone(start_page) != zone)
1368  		return NULL;
1369  
1370  	end_page = pfn_to_page(end_pfn);
1371  
1372  	/* This gives a shorter code than deriving page_zone(end_page) */
1373  	if (page_zone_id(start_page) != page_zone_id(end_page))
1374  		return NULL;
1375  
1376  	return start_page;
1377  }
1378  
1379  /*
1380   * The order of subdivision here is critical for the IO subsystem.
1381   * Please do not alter this order without good reasons and regression
1382   * testing. Specifically, as large blocks of memory are subdivided,
1383   * the order in which smaller blocks are delivered depends on the order
1384   * they're subdivided in this function. This is the primary factor
1385   * influencing the order in which pages are delivered to the IO
1386   * subsystem according to empirical testing, and this is also justified
1387   * by considering the behavior of a buddy system containing a single
1388   * large block of memory acted on by a series of small allocations.
1389   * This behavior is a critical factor in sglist merging's success.
1390   *
1391   * -- nyc
1392   */
expand(struct zone * zone,struct page * page,int low,int high,int migratetype)1393  static inline unsigned int expand(struct zone *zone, struct page *page, int low,
1394  				  int high, int migratetype)
1395  {
1396  	unsigned int size = 1 << high;
1397  	unsigned int nr_added = 0;
1398  
1399  	while (high > low) {
1400  		high--;
1401  		size >>= 1;
1402  		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
1403  
1404  		/*
1405  		 * Mark as guard pages (or page), that will allow to
1406  		 * merge back to allocator when buddy will be freed.
1407  		 * Corresponding page table entries will not be touched,
1408  		 * pages will stay not present in virtual address space
1409  		 */
1410  		if (set_page_guard(zone, &page[size], high))
1411  			continue;
1412  
1413  		__add_to_free_list(&page[size], zone, high, migratetype, false);
1414  		set_buddy_order(&page[size], high);
1415  		nr_added += size;
1416  	}
1417  
1418  	return nr_added;
1419  }
1420  
page_del_and_expand(struct zone * zone,struct page * page,int low,int high,int migratetype)1421  static __always_inline void page_del_and_expand(struct zone *zone,
1422  						struct page *page, int low,
1423  						int high, int migratetype)
1424  {
1425  	int nr_pages = 1 << high;
1426  
1427  	__del_page_from_free_list(page, zone, high, migratetype);
1428  	nr_pages -= expand(zone, page, low, high, migratetype);
1429  	account_freepages(zone, -nr_pages, migratetype);
1430  }
1431  
check_new_page_bad(struct page * page)1432  static void check_new_page_bad(struct page *page)
1433  {
1434  	if (unlikely(page->flags & __PG_HWPOISON)) {
1435  		/* Don't complain about hwpoisoned pages */
1436  		if (PageBuddy(page))
1437  			__ClearPageBuddy(page);
1438  		return;
1439  	}
1440  
1441  	bad_page(page,
1442  		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
1443  }
1444  
1445  /*
1446   * This page is about to be returned from the page allocator
1447   */
check_new_page(struct page * page)1448  static bool check_new_page(struct page *page)
1449  {
1450  	if (likely(page_expected_state(page,
1451  				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
1452  		return false;
1453  
1454  	check_new_page_bad(page);
1455  	return true;
1456  }
1457  
check_new_pages(struct page * page,unsigned int order)1458  static inline bool check_new_pages(struct page *page, unsigned int order)
1459  {
1460  	if (is_check_pages_enabled()) {
1461  		for (int i = 0; i < (1 << order); i++) {
1462  			struct page *p = page + i;
1463  
1464  			if (check_new_page(p))
1465  				return true;
1466  		}
1467  	}
1468  
1469  	return false;
1470  }
1471  
should_skip_kasan_unpoison(gfp_t flags)1472  static inline bool should_skip_kasan_unpoison(gfp_t flags)
1473  {
1474  	/* Don't skip if a software KASAN mode is enabled. */
1475  	if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
1476  	    IS_ENABLED(CONFIG_KASAN_SW_TAGS))
1477  		return false;
1478  
1479  	/* Skip, if hardware tag-based KASAN is not enabled. */
1480  	if (!kasan_hw_tags_enabled())
1481  		return true;
1482  
1483  	/*
1484  	 * With hardware tag-based KASAN enabled, skip if this has been
1485  	 * requested via __GFP_SKIP_KASAN.
1486  	 */
1487  	return flags & __GFP_SKIP_KASAN;
1488  }
1489  
should_skip_init(gfp_t flags)1490  static inline bool should_skip_init(gfp_t flags)
1491  {
1492  	/* Don't skip, if hardware tag-based KASAN is not enabled. */
1493  	if (!kasan_hw_tags_enabled())
1494  		return false;
1495  
1496  	/* For hardware tag-based KASAN, skip if requested. */
1497  	return (flags & __GFP_SKIP_ZERO);
1498  }
1499  
post_alloc_hook(struct page * page,unsigned int order,gfp_t gfp_flags)1500  inline void post_alloc_hook(struct page *page, unsigned int order,
1501  				gfp_t gfp_flags)
1502  {
1503  	bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) &&
1504  			!should_skip_init(gfp_flags);
1505  	bool zero_tags = init && (gfp_flags & __GFP_ZEROTAGS);
1506  	int i;
1507  
1508  	set_page_private(page, 0);
1509  	set_page_refcounted(page);
1510  
1511  	arch_alloc_page(page, order);
1512  	debug_pagealloc_map_pages(page, 1 << order);
1513  
1514  	/*
1515  	 * Page unpoisoning must happen before memory initialization.
1516  	 * Otherwise, the poison pattern will be overwritten for __GFP_ZERO
1517  	 * allocations and the page unpoisoning code will complain.
1518  	 */
1519  	kernel_unpoison_pages(page, 1 << order);
1520  
1521  	/*
1522  	 * As memory initialization might be integrated into KASAN,
1523  	 * KASAN unpoisoning and memory initializion code must be
1524  	 * kept together to avoid discrepancies in behavior.
1525  	 */
1526  
1527  	/*
1528  	 * If memory tags should be zeroed
1529  	 * (which happens only when memory should be initialized as well).
1530  	 */
1531  	if (zero_tags) {
1532  		/* Initialize both memory and memory tags. */
1533  		for (i = 0; i != 1 << order; ++i)
1534  			tag_clear_highpage(page + i);
1535  
1536  		/* Take note that memory was initialized by the loop above. */
1537  		init = false;
1538  	}
1539  	if (!should_skip_kasan_unpoison(gfp_flags) &&
1540  	    kasan_unpoison_pages(page, order, init)) {
1541  		/* Take note that memory was initialized by KASAN. */
1542  		if (kasan_has_integrated_init())
1543  			init = false;
1544  	} else {
1545  		/*
1546  		 * If memory tags have not been set by KASAN, reset the page
1547  		 * tags to ensure page_address() dereferencing does not fault.
1548  		 */
1549  		for (i = 0; i != 1 << order; ++i)
1550  			page_kasan_tag_reset(page + i);
1551  	}
1552  	/* If memory is still not initialized, initialize it now. */
1553  	if (init)
1554  		kernel_init_pages(page, 1 << order);
1555  
1556  	set_page_owner(page, order, gfp_flags);
1557  	page_table_check_alloc(page, order);
1558  	pgalloc_tag_add(page, current, 1 << order);
1559  }
1560  
prep_new_page(struct page * page,unsigned int order,gfp_t gfp_flags,unsigned int alloc_flags)1561  static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
1562  							unsigned int alloc_flags)
1563  {
1564  	post_alloc_hook(page, order, gfp_flags);
1565  
1566  	if (order && (gfp_flags & __GFP_COMP))
1567  		prep_compound_page(page, order);
1568  
1569  	/*
1570  	 * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
1571  	 * allocate the page. The expectation is that the caller is taking
1572  	 * steps that will free more memory. The caller should avoid the page
1573  	 * being used for !PFMEMALLOC purposes.
1574  	 */
1575  	if (alloc_flags & ALLOC_NO_WATERMARKS)
1576  		set_page_pfmemalloc(page);
1577  	else
1578  		clear_page_pfmemalloc(page);
1579  }
1580  
1581  /*
1582   * Go through the free lists for the given migratetype and remove
1583   * the smallest available page from the freelists
1584   */
1585  static __always_inline
__rmqueue_smallest(struct zone * zone,unsigned int order,int migratetype)1586  struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
1587  						int migratetype)
1588  {
1589  	unsigned int current_order;
1590  	struct free_area *area;
1591  	struct page *page;
1592  
1593  	/* Find a page of the appropriate size in the preferred list */
1594  	for (current_order = order; current_order < NR_PAGE_ORDERS; ++current_order) {
1595  		area = &(zone->free_area[current_order]);
1596  		page = get_page_from_free_area(area, migratetype);
1597  		if (!page)
1598  			continue;
1599  
1600  		page_del_and_expand(zone, page, order, current_order,
1601  				    migratetype);
1602  		trace_mm_page_alloc_zone_locked(page, order, migratetype,
1603  				pcp_allowed_order(order) &&
1604  				migratetype < MIGRATE_PCPTYPES);
1605  		return page;
1606  	}
1607  
1608  	return NULL;
1609  }
1610  
1611  
1612  /*
1613   * This array describes the order lists are fallen back to when
1614   * the free lists for the desirable migrate type are depleted
1615   *
1616   * The other migratetypes do not have fallbacks.
1617   */
1618  static int fallbacks[MIGRATE_PCPTYPES][MIGRATE_PCPTYPES - 1] = {
1619  	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE   },
1620  	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
1621  	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE   },
1622  };
1623  
1624  #ifdef CONFIG_CMA
__rmqueue_cma_fallback(struct zone * zone,unsigned int order)1625  static __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone,
1626  					unsigned int order)
1627  {
1628  	return __rmqueue_smallest(zone, order, MIGRATE_CMA);
1629  }
1630  #else
__rmqueue_cma_fallback(struct zone * zone,unsigned int order)1631  static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
1632  					unsigned int order) { return NULL; }
1633  #endif
1634  
1635  /*
1636   * Change the type of a block and move all its free pages to that
1637   * type's freelist.
1638   */
__move_freepages_block(struct zone * zone,unsigned long start_pfn,int old_mt,int new_mt)1639  static int __move_freepages_block(struct zone *zone, unsigned long start_pfn,
1640  				  int old_mt, int new_mt)
1641  {
1642  	struct page *page;
1643  	unsigned long pfn, end_pfn;
1644  	unsigned int order;
1645  	int pages_moved = 0;
1646  
1647  	VM_WARN_ON(start_pfn & (pageblock_nr_pages - 1));
1648  	end_pfn = pageblock_end_pfn(start_pfn);
1649  
1650  	for (pfn = start_pfn; pfn < end_pfn;) {
1651  		page = pfn_to_page(pfn);
1652  		if (!PageBuddy(page)) {
1653  			pfn++;
1654  			continue;
1655  		}
1656  
1657  		/* Make sure we are not inadvertently changing nodes */
1658  		VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
1659  		VM_BUG_ON_PAGE(page_zone(page) != zone, page);
1660  
1661  		order = buddy_order(page);
1662  
1663  		move_to_free_list(page, zone, order, old_mt, new_mt);
1664  
1665  		pfn += 1 << order;
1666  		pages_moved += 1 << order;
1667  	}
1668  
1669  	set_pageblock_migratetype(pfn_to_page(start_pfn), new_mt);
1670  
1671  	return pages_moved;
1672  }
1673  
prep_move_freepages_block(struct zone * zone,struct page * page,unsigned long * start_pfn,int * num_free,int * num_movable)1674  static bool prep_move_freepages_block(struct zone *zone, struct page *page,
1675  				      unsigned long *start_pfn,
1676  				      int *num_free, int *num_movable)
1677  {
1678  	unsigned long pfn, start, end;
1679  
1680  	pfn = page_to_pfn(page);
1681  	start = pageblock_start_pfn(pfn);
1682  	end = pageblock_end_pfn(pfn);
1683  
1684  	/*
1685  	 * The caller only has the lock for @zone, don't touch ranges
1686  	 * that straddle into other zones. While we could move part of
1687  	 * the range that's inside the zone, this call is usually
1688  	 * accompanied by other operations such as migratetype updates
1689  	 * which also should be locked.
1690  	 */
1691  	if (!zone_spans_pfn(zone, start))
1692  		return false;
1693  	if (!zone_spans_pfn(zone, end - 1))
1694  		return false;
1695  
1696  	*start_pfn = start;
1697  
1698  	if (num_free) {
1699  		*num_free = 0;
1700  		*num_movable = 0;
1701  		for (pfn = start; pfn < end;) {
1702  			page = pfn_to_page(pfn);
1703  			if (PageBuddy(page)) {
1704  				int nr = 1 << buddy_order(page);
1705  
1706  				*num_free += nr;
1707  				pfn += nr;
1708  				continue;
1709  			}
1710  			/*
1711  			 * We assume that pages that could be isolated for
1712  			 * migration are movable. But we don't actually try
1713  			 * isolating, as that would be expensive.
1714  			 */
1715  			if (PageLRU(page) || __PageMovable(page))
1716  				(*num_movable)++;
1717  			pfn++;
1718  		}
1719  	}
1720  
1721  	return true;
1722  }
1723  
move_freepages_block(struct zone * zone,struct page * page,int old_mt,int new_mt)1724  static int move_freepages_block(struct zone *zone, struct page *page,
1725  				int old_mt, int new_mt)
1726  {
1727  	unsigned long start_pfn;
1728  
1729  	if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL))
1730  		return -1;
1731  
1732  	return __move_freepages_block(zone, start_pfn, old_mt, new_mt);
1733  }
1734  
1735  #ifdef CONFIG_MEMORY_ISOLATION
1736  /* Look for a buddy that straddles start_pfn */
find_large_buddy(unsigned long start_pfn)1737  static unsigned long find_large_buddy(unsigned long start_pfn)
1738  {
1739  	int order = 0;
1740  	struct page *page;
1741  	unsigned long pfn = start_pfn;
1742  
1743  	while (!PageBuddy(page = pfn_to_page(pfn))) {
1744  		/* Nothing found */
1745  		if (++order > MAX_PAGE_ORDER)
1746  			return start_pfn;
1747  		pfn &= ~0UL << order;
1748  	}
1749  
1750  	/*
1751  	 * Found a preceding buddy, but does it straddle?
1752  	 */
1753  	if (pfn + (1 << buddy_order(page)) > start_pfn)
1754  		return pfn;
1755  
1756  	/* Nothing found */
1757  	return start_pfn;
1758  }
1759  
1760  /**
1761   * move_freepages_block_isolate - move free pages in block for page isolation
1762   * @zone: the zone
1763   * @page: the pageblock page
1764   * @migratetype: migratetype to set on the pageblock
1765   *
1766   * This is similar to move_freepages_block(), but handles the special
1767   * case encountered in page isolation, where the block of interest
1768   * might be part of a larger buddy spanning multiple pageblocks.
1769   *
1770   * Unlike the regular page allocator path, which moves pages while
1771   * stealing buddies off the freelist, page isolation is interested in
1772   * arbitrary pfn ranges that may have overlapping buddies on both ends.
1773   *
1774   * This function handles that. Straddling buddies are split into
1775   * individual pageblocks. Only the block of interest is moved.
1776   *
1777   * Returns %true if pages could be moved, %false otherwise.
1778   */
move_freepages_block_isolate(struct zone * zone,struct page * page,int migratetype)1779  bool move_freepages_block_isolate(struct zone *zone, struct page *page,
1780  				  int migratetype)
1781  {
1782  	unsigned long start_pfn, pfn;
1783  
1784  	if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL))
1785  		return false;
1786  
1787  	/* No splits needed if buddies can't span multiple blocks */
1788  	if (pageblock_order == MAX_PAGE_ORDER)
1789  		goto move;
1790  
1791  	/* We're a tail block in a larger buddy */
1792  	pfn = find_large_buddy(start_pfn);
1793  	if (pfn != start_pfn) {
1794  		struct page *buddy = pfn_to_page(pfn);
1795  		int order = buddy_order(buddy);
1796  
1797  		del_page_from_free_list(buddy, zone, order,
1798  					get_pfnblock_migratetype(buddy, pfn));
1799  		set_pageblock_migratetype(page, migratetype);
1800  		split_large_buddy(zone, buddy, pfn, order, FPI_NONE);
1801  		return true;
1802  	}
1803  
1804  	/* We're the starting block of a larger buddy */
1805  	if (PageBuddy(page) && buddy_order(page) > pageblock_order) {
1806  		int order = buddy_order(page);
1807  
1808  		del_page_from_free_list(page, zone, order,
1809  					get_pfnblock_migratetype(page, pfn));
1810  		set_pageblock_migratetype(page, migratetype);
1811  		split_large_buddy(zone, page, pfn, order, FPI_NONE);
1812  		return true;
1813  	}
1814  move:
1815  	__move_freepages_block(zone, start_pfn,
1816  			       get_pfnblock_migratetype(page, start_pfn),
1817  			       migratetype);
1818  	return true;
1819  }
1820  #endif /* CONFIG_MEMORY_ISOLATION */
1821  
change_pageblock_range(struct page * pageblock_page,int start_order,int migratetype)1822  static void change_pageblock_range(struct page *pageblock_page,
1823  					int start_order, int migratetype)
1824  {
1825  	int nr_pageblocks = 1 << (start_order - pageblock_order);
1826  
1827  	while (nr_pageblocks--) {
1828  		set_pageblock_migratetype(pageblock_page, migratetype);
1829  		pageblock_page += pageblock_nr_pages;
1830  	}
1831  }
1832  
1833  /*
1834   * When we are falling back to another migratetype during allocation, try to
1835   * steal extra free pages from the same pageblocks to satisfy further
1836   * allocations, instead of polluting multiple pageblocks.
1837   *
1838   * If we are stealing a relatively large buddy page, it is likely there will
1839   * be more free pages in the pageblock, so try to steal them all. For
1840   * reclaimable and unmovable allocations, we steal regardless of page size,
1841   * as fragmentation caused by those allocations polluting movable pageblocks
1842   * is worse than movable allocations stealing from unmovable and reclaimable
1843   * pageblocks.
1844   */
can_steal_fallback(unsigned int order,int start_mt)1845  static bool can_steal_fallback(unsigned int order, int start_mt)
1846  {
1847  	/*
1848  	 * Leaving this order check is intended, although there is
1849  	 * relaxed order check in next check. The reason is that
1850  	 * we can actually steal whole pageblock if this condition met,
1851  	 * but, below check doesn't guarantee it and that is just heuristic
1852  	 * so could be changed anytime.
1853  	 */
1854  	if (order >= pageblock_order)
1855  		return true;
1856  
1857  	if (order >= pageblock_order / 2 ||
1858  		start_mt == MIGRATE_RECLAIMABLE ||
1859  		start_mt == MIGRATE_UNMOVABLE ||
1860  		page_group_by_mobility_disabled)
1861  		return true;
1862  
1863  	return false;
1864  }
1865  
boost_watermark(struct zone * zone)1866  static inline bool boost_watermark(struct zone *zone)
1867  {
1868  	unsigned long max_boost;
1869  
1870  	if (!watermark_boost_factor)
1871  		return false;
1872  	/*
1873  	 * Don't bother in zones that are unlikely to produce results.
1874  	 * On small machines, including kdump capture kernels running
1875  	 * in a small area, boosting the watermark can cause an out of
1876  	 * memory situation immediately.
1877  	 */
1878  	if ((pageblock_nr_pages * 4) > zone_managed_pages(zone))
1879  		return false;
1880  
1881  	max_boost = mult_frac(zone->_watermark[WMARK_HIGH],
1882  			watermark_boost_factor, 10000);
1883  
1884  	/*
1885  	 * high watermark may be uninitialised if fragmentation occurs
1886  	 * very early in boot so do not boost. We do not fall
1887  	 * through and boost by pageblock_nr_pages as failing
1888  	 * allocations that early means that reclaim is not going
1889  	 * to help and it may even be impossible to reclaim the
1890  	 * boosted watermark resulting in a hang.
1891  	 */
1892  	if (!max_boost)
1893  		return false;
1894  
1895  	max_boost = max(pageblock_nr_pages, max_boost);
1896  
1897  	zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages,
1898  		max_boost);
1899  
1900  	return true;
1901  }
1902  
1903  /*
1904   * This function implements actual steal behaviour. If order is large enough, we
1905   * can claim the whole pageblock for the requested migratetype. If not, we check
1906   * the pageblock for constituent pages; if at least half of the pages are free
1907   * or compatible, we can still claim the whole block, so pages freed in the
1908   * future will be put on the correct free list. Otherwise, we isolate exactly
1909   * the order we need from the fallback block and leave its migratetype alone.
1910   */
1911  static struct page *
steal_suitable_fallback(struct zone * zone,struct page * page,int current_order,int order,int start_type,unsigned int alloc_flags,bool whole_block)1912  steal_suitable_fallback(struct zone *zone, struct page *page,
1913  			int current_order, int order, int start_type,
1914  			unsigned int alloc_flags, bool whole_block)
1915  {
1916  	int free_pages, movable_pages, alike_pages;
1917  	unsigned long start_pfn;
1918  	int block_type;
1919  
1920  	block_type = get_pageblock_migratetype(page);
1921  
1922  	/*
1923  	 * This can happen due to races and we want to prevent broken
1924  	 * highatomic accounting.
1925  	 */
1926  	if (is_migrate_highatomic(block_type))
1927  		goto single_page;
1928  
1929  	/* Take ownership for orders >= pageblock_order */
1930  	if (current_order >= pageblock_order) {
1931  		unsigned int nr_added;
1932  
1933  		del_page_from_free_list(page, zone, current_order, block_type);
1934  		change_pageblock_range(page, current_order, start_type);
1935  		nr_added = expand(zone, page, order, current_order, start_type);
1936  		account_freepages(zone, nr_added, start_type);
1937  		return page;
1938  	}
1939  
1940  	/*
1941  	 * Boost watermarks to increase reclaim pressure to reduce the
1942  	 * likelihood of future fallbacks. Wake kswapd now as the node
1943  	 * may be balanced overall and kswapd will not wake naturally.
1944  	 */
1945  	if (boost_watermark(zone) && (alloc_flags & ALLOC_KSWAPD))
1946  		set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
1947  
1948  	/* We are not allowed to try stealing from the whole block */
1949  	if (!whole_block)
1950  		goto single_page;
1951  
1952  	/* moving whole block can fail due to zone boundary conditions */
1953  	if (!prep_move_freepages_block(zone, page, &start_pfn, &free_pages,
1954  				       &movable_pages))
1955  		goto single_page;
1956  
1957  	/*
1958  	 * Determine how many pages are compatible with our allocation.
1959  	 * For movable allocation, it's the number of movable pages which
1960  	 * we just obtained. For other types it's a bit more tricky.
1961  	 */
1962  	if (start_type == MIGRATE_MOVABLE) {
1963  		alike_pages = movable_pages;
1964  	} else {
1965  		/*
1966  		 * If we are falling back a RECLAIMABLE or UNMOVABLE allocation
1967  		 * to MOVABLE pageblock, consider all non-movable pages as
1968  		 * compatible. If it's UNMOVABLE falling back to RECLAIMABLE or
1969  		 * vice versa, be conservative since we can't distinguish the
1970  		 * exact migratetype of non-movable pages.
1971  		 */
1972  		if (block_type == MIGRATE_MOVABLE)
1973  			alike_pages = pageblock_nr_pages
1974  						- (free_pages + movable_pages);
1975  		else
1976  			alike_pages = 0;
1977  	}
1978  	/*
1979  	 * If a sufficient number of pages in the block are either free or of
1980  	 * compatible migratability as our allocation, claim the whole block.
1981  	 */
1982  	if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
1983  			page_group_by_mobility_disabled) {
1984  		__move_freepages_block(zone, start_pfn, block_type, start_type);
1985  		return __rmqueue_smallest(zone, order, start_type);
1986  	}
1987  
1988  single_page:
1989  	page_del_and_expand(zone, page, order, current_order, block_type);
1990  	return page;
1991  }
1992  
1993  /*
1994   * Check whether there is a suitable fallback freepage with requested order.
1995   * If only_stealable is true, this function returns fallback_mt only if
1996   * we can steal other freepages all together. This would help to reduce
1997   * fragmentation due to mixed migratetype pages in one pageblock.
1998   */
find_suitable_fallback(struct free_area * area,unsigned int order,int migratetype,bool only_stealable,bool * can_steal)1999  int find_suitable_fallback(struct free_area *area, unsigned int order,
2000  			int migratetype, bool only_stealable, bool *can_steal)
2001  {
2002  	int i;
2003  	int fallback_mt;
2004  
2005  	if (area->nr_free == 0)
2006  		return -1;
2007  
2008  	*can_steal = false;
2009  	for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) {
2010  		fallback_mt = fallbacks[migratetype][i];
2011  		if (free_area_empty(area, fallback_mt))
2012  			continue;
2013  
2014  		if (can_steal_fallback(order, migratetype))
2015  			*can_steal = true;
2016  
2017  		if (!only_stealable)
2018  			return fallback_mt;
2019  
2020  		if (*can_steal)
2021  			return fallback_mt;
2022  	}
2023  
2024  	return -1;
2025  }
2026  
2027  /*
2028   * Reserve the pageblock(s) surrounding an allocation request for
2029   * exclusive use of high-order atomic allocations if there are no
2030   * empty page blocks that contain a page with a suitable order
2031   */
reserve_highatomic_pageblock(struct page * page,int order,struct zone * zone)2032  static void reserve_highatomic_pageblock(struct page *page, int order,
2033  					 struct zone *zone)
2034  {
2035  	int mt;
2036  	unsigned long max_managed, flags;
2037  
2038  	/*
2039  	 * The number reserved as: minimum is 1 pageblock, maximum is
2040  	 * roughly 1% of a zone. But if 1% of a zone falls below a
2041  	 * pageblock size, then don't reserve any pageblocks.
2042  	 * Check is race-prone but harmless.
2043  	 */
2044  	if ((zone_managed_pages(zone) / 100) < pageblock_nr_pages)
2045  		return;
2046  	max_managed = ALIGN((zone_managed_pages(zone) / 100), pageblock_nr_pages);
2047  	if (zone->nr_reserved_highatomic >= max_managed)
2048  		return;
2049  
2050  	spin_lock_irqsave(&zone->lock, flags);
2051  
2052  	/* Recheck the nr_reserved_highatomic limit under the lock */
2053  	if (zone->nr_reserved_highatomic >= max_managed)
2054  		goto out_unlock;
2055  
2056  	/* Yoink! */
2057  	mt = get_pageblock_migratetype(page);
2058  	/* Only reserve normal pageblocks (i.e., they can merge with others) */
2059  	if (!migratetype_is_mergeable(mt))
2060  		goto out_unlock;
2061  
2062  	if (order < pageblock_order) {
2063  		if (move_freepages_block(zone, page, mt, MIGRATE_HIGHATOMIC) == -1)
2064  			goto out_unlock;
2065  		zone->nr_reserved_highatomic += pageblock_nr_pages;
2066  	} else {
2067  		change_pageblock_range(page, order, MIGRATE_HIGHATOMIC);
2068  		zone->nr_reserved_highatomic += 1 << order;
2069  	}
2070  
2071  out_unlock:
2072  	spin_unlock_irqrestore(&zone->lock, flags);
2073  }
2074  
2075  /*
2076   * Used when an allocation is about to fail under memory pressure. This
2077   * potentially hurts the reliability of high-order allocations when under
2078   * intense memory pressure but failed atomic allocations should be easier
2079   * to recover from than an OOM.
2080   *
2081   * If @force is true, try to unreserve pageblocks even though highatomic
2082   * pageblock is exhausted.
2083   */
unreserve_highatomic_pageblock(const struct alloc_context * ac,bool force)2084  static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
2085  						bool force)
2086  {
2087  	struct zonelist *zonelist = ac->zonelist;
2088  	unsigned long flags;
2089  	struct zoneref *z;
2090  	struct zone *zone;
2091  	struct page *page;
2092  	int order;
2093  	int ret;
2094  
2095  	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
2096  								ac->nodemask) {
2097  		/*
2098  		 * Preserve at least one pageblock unless memory pressure
2099  		 * is really high.
2100  		 */
2101  		if (!force && zone->nr_reserved_highatomic <=
2102  					pageblock_nr_pages)
2103  			continue;
2104  
2105  		spin_lock_irqsave(&zone->lock, flags);
2106  		for (order = 0; order < NR_PAGE_ORDERS; order++) {
2107  			struct free_area *area = &(zone->free_area[order]);
2108  			int mt;
2109  
2110  			page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
2111  			if (!page)
2112  				continue;
2113  
2114  			mt = get_pageblock_migratetype(page);
2115  			/*
2116  			 * In page freeing path, migratetype change is racy so
2117  			 * we can counter several free pages in a pageblock
2118  			 * in this loop although we changed the pageblock type
2119  			 * from highatomic to ac->migratetype. So we should
2120  			 * adjust the count once.
2121  			 */
2122  			if (is_migrate_highatomic(mt)) {
2123  				unsigned long size;
2124  				/*
2125  				 * It should never happen but changes to
2126  				 * locking could inadvertently allow a per-cpu
2127  				 * drain to add pages to MIGRATE_HIGHATOMIC
2128  				 * while unreserving so be safe and watch for
2129  				 * underflows.
2130  				 */
2131  				size = max(pageblock_nr_pages, 1UL << order);
2132  				size = min(size, zone->nr_reserved_highatomic);
2133  				zone->nr_reserved_highatomic -= size;
2134  			}
2135  
2136  			/*
2137  			 * Convert to ac->migratetype and avoid the normal
2138  			 * pageblock stealing heuristics. Minimally, the caller
2139  			 * is doing the work and needs the pages. More
2140  			 * importantly, if the block was always converted to
2141  			 * MIGRATE_UNMOVABLE or another type then the number
2142  			 * of pageblocks that cannot be completely freed
2143  			 * may increase.
2144  			 */
2145  			if (order < pageblock_order)
2146  				ret = move_freepages_block(zone, page, mt,
2147  							   ac->migratetype);
2148  			else {
2149  				move_to_free_list(page, zone, order, mt,
2150  						  ac->migratetype);
2151  				change_pageblock_range(page, order,
2152  						       ac->migratetype);
2153  				ret = 1;
2154  			}
2155  			/*
2156  			 * Reserving the block(s) already succeeded,
2157  			 * so this should not fail on zone boundaries.
2158  			 */
2159  			WARN_ON_ONCE(ret == -1);
2160  			if (ret > 0) {
2161  				spin_unlock_irqrestore(&zone->lock, flags);
2162  				return ret;
2163  			}
2164  		}
2165  		spin_unlock_irqrestore(&zone->lock, flags);
2166  	}
2167  
2168  	return false;
2169  }
2170  
2171  /*
2172   * Try finding a free buddy page on the fallback list and put it on the free
2173   * list of requested migratetype, possibly along with other pages from the same
2174   * block, depending on fragmentation avoidance heuristics. Returns true if
2175   * fallback was found so that __rmqueue_smallest() can grab it.
2176   *
2177   * The use of signed ints for order and current_order is a deliberate
2178   * deviation from the rest of this file, to make the for loop
2179   * condition simpler.
2180   */
2181  static __always_inline struct page *
__rmqueue_fallback(struct zone * zone,int order,int start_migratetype,unsigned int alloc_flags)2182  __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
2183  						unsigned int alloc_flags)
2184  {
2185  	struct free_area *area;
2186  	int current_order;
2187  	int min_order = order;
2188  	struct page *page;
2189  	int fallback_mt;
2190  	bool can_steal;
2191  
2192  	/*
2193  	 * Do not steal pages from freelists belonging to other pageblocks
2194  	 * i.e. orders < pageblock_order. If there are no local zones free,
2195  	 * the zonelists will be reiterated without ALLOC_NOFRAGMENT.
2196  	 */
2197  	if (order < pageblock_order && alloc_flags & ALLOC_NOFRAGMENT)
2198  		min_order = pageblock_order;
2199  
2200  	/*
2201  	 * Find the largest available free page in the other list. This roughly
2202  	 * approximates finding the pageblock with the most free pages, which
2203  	 * would be too costly to do exactly.
2204  	 */
2205  	for (current_order = MAX_PAGE_ORDER; current_order >= min_order;
2206  				--current_order) {
2207  		area = &(zone->free_area[current_order]);
2208  		fallback_mt = find_suitable_fallback(area, current_order,
2209  				start_migratetype, false, &can_steal);
2210  		if (fallback_mt == -1)
2211  			continue;
2212  
2213  		/*
2214  		 * We cannot steal all free pages from the pageblock and the
2215  		 * requested migratetype is movable. In that case it's better to
2216  		 * steal and split the smallest available page instead of the
2217  		 * largest available page, because even if the next movable
2218  		 * allocation falls back into a different pageblock than this
2219  		 * one, it won't cause permanent fragmentation.
2220  		 */
2221  		if (!can_steal && start_migratetype == MIGRATE_MOVABLE
2222  					&& current_order > order)
2223  			goto find_smallest;
2224  
2225  		goto do_steal;
2226  	}
2227  
2228  	return NULL;
2229  
2230  find_smallest:
2231  	for (current_order = order; current_order < NR_PAGE_ORDERS; current_order++) {
2232  		area = &(zone->free_area[current_order]);
2233  		fallback_mt = find_suitable_fallback(area, current_order,
2234  				start_migratetype, false, &can_steal);
2235  		if (fallback_mt != -1)
2236  			break;
2237  	}
2238  
2239  	/*
2240  	 * This should not happen - we already found a suitable fallback
2241  	 * when looking for the largest page.
2242  	 */
2243  	VM_BUG_ON(current_order > MAX_PAGE_ORDER);
2244  
2245  do_steal:
2246  	page = get_page_from_free_area(area, fallback_mt);
2247  
2248  	/* take off list, maybe claim block, expand remainder */
2249  	page = steal_suitable_fallback(zone, page, current_order, order,
2250  				       start_migratetype, alloc_flags, can_steal);
2251  
2252  	trace_mm_page_alloc_extfrag(page, order, current_order,
2253  		start_migratetype, fallback_mt);
2254  
2255  	return page;
2256  }
2257  
2258  /*
2259   * Do the hard work of removing an element from the buddy allocator.
2260   * Call me with the zone->lock already held.
2261   */
2262  static __always_inline struct page *
__rmqueue(struct zone * zone,unsigned int order,int migratetype,unsigned int alloc_flags)2263  __rmqueue(struct zone *zone, unsigned int order, int migratetype,
2264  						unsigned int alloc_flags)
2265  {
2266  	struct page *page;
2267  
2268  	if (IS_ENABLED(CONFIG_CMA)) {
2269  		/*
2270  		 * Balance movable allocations between regular and CMA areas by
2271  		 * allocating from CMA when over half of the zone's free memory
2272  		 * is in the CMA area.
2273  		 */
2274  		if (alloc_flags & ALLOC_CMA &&
2275  		    zone_page_state(zone, NR_FREE_CMA_PAGES) >
2276  		    zone_page_state(zone, NR_FREE_PAGES) / 2) {
2277  			page = __rmqueue_cma_fallback(zone, order);
2278  			if (page)
2279  				return page;
2280  		}
2281  	}
2282  
2283  	page = __rmqueue_smallest(zone, order, migratetype);
2284  	if (unlikely(!page)) {
2285  		if (alloc_flags & ALLOC_CMA)
2286  			page = __rmqueue_cma_fallback(zone, order);
2287  
2288  		if (!page)
2289  			page = __rmqueue_fallback(zone, order, migratetype,
2290  						  alloc_flags);
2291  	}
2292  	return page;
2293  }
2294  
2295  /*
2296   * Obtain a specified number of elements from the buddy allocator, all under
2297   * a single hold of the lock, for efficiency.  Add them to the supplied list.
2298   * Returns the number of new pages which were placed at *list.
2299   */
rmqueue_bulk(struct zone * zone,unsigned int order,unsigned long count,struct list_head * list,int migratetype,unsigned int alloc_flags)2300  static int rmqueue_bulk(struct zone *zone, unsigned int order,
2301  			unsigned long count, struct list_head *list,
2302  			int migratetype, unsigned int alloc_flags)
2303  {
2304  	unsigned long flags;
2305  	int i;
2306  
2307  	spin_lock_irqsave(&zone->lock, flags);
2308  	for (i = 0; i < count; ++i) {
2309  		struct page *page = __rmqueue(zone, order, migratetype,
2310  								alloc_flags);
2311  		if (unlikely(page == NULL))
2312  			break;
2313  
2314  		/*
2315  		 * Split buddy pages returned by expand() are received here in
2316  		 * physical page order. The page is added to the tail of
2317  		 * caller's list. From the callers perspective, the linked list
2318  		 * is ordered by page number under some conditions. This is
2319  		 * useful for IO devices that can forward direction from the
2320  		 * head, thus also in the physical page order. This is useful
2321  		 * for IO devices that can merge IO requests if the physical
2322  		 * pages are ordered properly.
2323  		 */
2324  		list_add_tail(&page->pcp_list, list);
2325  	}
2326  	spin_unlock_irqrestore(&zone->lock, flags);
2327  
2328  	return i;
2329  }
2330  
2331  /*
2332   * Called from the vmstat counter updater to decay the PCP high.
2333   * Return whether there are addition works to do.
2334   */
decay_pcp_high(struct zone * zone,struct per_cpu_pages * pcp)2335  int decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp)
2336  {
2337  	int high_min, to_drain, batch;
2338  	int todo = 0;
2339  
2340  	high_min = READ_ONCE(pcp->high_min);
2341  	batch = READ_ONCE(pcp->batch);
2342  	/*
2343  	 * Decrease pcp->high periodically to try to free possible
2344  	 * idle PCP pages.  And, avoid to free too many pages to
2345  	 * control latency.  This caps pcp->high decrement too.
2346  	 */
2347  	if (pcp->high > high_min) {
2348  		pcp->high = max3(pcp->count - (batch << CONFIG_PCP_BATCH_SCALE_MAX),
2349  				 pcp->high - (pcp->high >> 3), high_min);
2350  		if (pcp->high > high_min)
2351  			todo++;
2352  	}
2353  
2354  	to_drain = pcp->count - pcp->high;
2355  	if (to_drain > 0) {
2356  		spin_lock(&pcp->lock);
2357  		free_pcppages_bulk(zone, to_drain, pcp, 0);
2358  		spin_unlock(&pcp->lock);
2359  		todo++;
2360  	}
2361  
2362  	return todo;
2363  }
2364  
2365  #ifdef CONFIG_NUMA
2366  /*
2367   * Called from the vmstat counter updater to drain pagesets of this
2368   * currently executing processor on remote nodes after they have
2369   * expired.
2370   */
drain_zone_pages(struct zone * zone,struct per_cpu_pages * pcp)2371  void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
2372  {
2373  	int to_drain, batch;
2374  
2375  	batch = READ_ONCE(pcp->batch);
2376  	to_drain = min(pcp->count, batch);
2377  	if (to_drain > 0) {
2378  		spin_lock(&pcp->lock);
2379  		free_pcppages_bulk(zone, to_drain, pcp, 0);
2380  		spin_unlock(&pcp->lock);
2381  	}
2382  }
2383  #endif
2384  
2385  /*
2386   * Drain pcplists of the indicated processor and zone.
2387   */
drain_pages_zone(unsigned int cpu,struct zone * zone)2388  static void drain_pages_zone(unsigned int cpu, struct zone *zone)
2389  {
2390  	struct per_cpu_pages *pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
2391  	int count;
2392  
2393  	do {
2394  		spin_lock(&pcp->lock);
2395  		count = pcp->count;
2396  		if (count) {
2397  			int to_drain = min(count,
2398  				pcp->batch << CONFIG_PCP_BATCH_SCALE_MAX);
2399  
2400  			free_pcppages_bulk(zone, to_drain, pcp, 0);
2401  			count -= to_drain;
2402  		}
2403  		spin_unlock(&pcp->lock);
2404  	} while (count);
2405  }
2406  
2407  /*
2408   * Drain pcplists of all zones on the indicated processor.
2409   */
drain_pages(unsigned int cpu)2410  static void drain_pages(unsigned int cpu)
2411  {
2412  	struct zone *zone;
2413  
2414  	for_each_populated_zone(zone) {
2415  		drain_pages_zone(cpu, zone);
2416  	}
2417  }
2418  
2419  /*
2420   * Spill all of this CPU's per-cpu pages back into the buddy allocator.
2421   */
drain_local_pages(struct zone * zone)2422  void drain_local_pages(struct zone *zone)
2423  {
2424  	int cpu = smp_processor_id();
2425  
2426  	if (zone)
2427  		drain_pages_zone(cpu, zone);
2428  	else
2429  		drain_pages(cpu);
2430  }
2431  
2432  /*
2433   * The implementation of drain_all_pages(), exposing an extra parameter to
2434   * drain on all cpus.
2435   *
2436   * drain_all_pages() is optimized to only execute on cpus where pcplists are
2437   * not empty. The check for non-emptiness can however race with a free to
2438   * pcplist that has not yet increased the pcp->count from 0 to 1. Callers
2439   * that need the guarantee that every CPU has drained can disable the
2440   * optimizing racy check.
2441   */
__drain_all_pages(struct zone * zone,bool force_all_cpus)2442  static void __drain_all_pages(struct zone *zone, bool force_all_cpus)
2443  {
2444  	int cpu;
2445  
2446  	/*
2447  	 * Allocate in the BSS so we won't require allocation in
2448  	 * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
2449  	 */
2450  	static cpumask_t cpus_with_pcps;
2451  
2452  	/*
2453  	 * Do not drain if one is already in progress unless it's specific to
2454  	 * a zone. Such callers are primarily CMA and memory hotplug and need
2455  	 * the drain to be complete when the call returns.
2456  	 */
2457  	if (unlikely(!mutex_trylock(&pcpu_drain_mutex))) {
2458  		if (!zone)
2459  			return;
2460  		mutex_lock(&pcpu_drain_mutex);
2461  	}
2462  
2463  	/*
2464  	 * We don't care about racing with CPU hotplug event
2465  	 * as offline notification will cause the notified
2466  	 * cpu to drain that CPU pcps and on_each_cpu_mask
2467  	 * disables preemption as part of its processing
2468  	 */
2469  	for_each_online_cpu(cpu) {
2470  		struct per_cpu_pages *pcp;
2471  		struct zone *z;
2472  		bool has_pcps = false;
2473  
2474  		if (force_all_cpus) {
2475  			/*
2476  			 * The pcp.count check is racy, some callers need a
2477  			 * guarantee that no cpu is missed.
2478  			 */
2479  			has_pcps = true;
2480  		} else if (zone) {
2481  			pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
2482  			if (pcp->count)
2483  				has_pcps = true;
2484  		} else {
2485  			for_each_populated_zone(z) {
2486  				pcp = per_cpu_ptr(z->per_cpu_pageset, cpu);
2487  				if (pcp->count) {
2488  					has_pcps = true;
2489  					break;
2490  				}
2491  			}
2492  		}
2493  
2494  		if (has_pcps)
2495  			cpumask_set_cpu(cpu, &cpus_with_pcps);
2496  		else
2497  			cpumask_clear_cpu(cpu, &cpus_with_pcps);
2498  	}
2499  
2500  	for_each_cpu(cpu, &cpus_with_pcps) {
2501  		if (zone)
2502  			drain_pages_zone(cpu, zone);
2503  		else
2504  			drain_pages(cpu);
2505  	}
2506  
2507  	mutex_unlock(&pcpu_drain_mutex);
2508  }
2509  
2510  /*
2511   * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
2512   *
2513   * When zone parameter is non-NULL, spill just the single zone's pages.
2514   */
drain_all_pages(struct zone * zone)2515  void drain_all_pages(struct zone *zone)
2516  {
2517  	__drain_all_pages(zone, false);
2518  }
2519  
nr_pcp_free(struct per_cpu_pages * pcp,int batch,int high,bool free_high)2520  static int nr_pcp_free(struct per_cpu_pages *pcp, int batch, int high, bool free_high)
2521  {
2522  	int min_nr_free, max_nr_free;
2523  
2524  	/* Free as much as possible if batch freeing high-order pages. */
2525  	if (unlikely(free_high))
2526  		return min(pcp->count, batch << CONFIG_PCP_BATCH_SCALE_MAX);
2527  
2528  	/* Check for PCP disabled or boot pageset */
2529  	if (unlikely(high < batch))
2530  		return 1;
2531  
2532  	/* Leave at least pcp->batch pages on the list */
2533  	min_nr_free = batch;
2534  	max_nr_free = high - batch;
2535  
2536  	/*
2537  	 * Increase the batch number to the number of the consecutive
2538  	 * freed pages to reduce zone lock contention.
2539  	 */
2540  	batch = clamp_t(int, pcp->free_count, min_nr_free, max_nr_free);
2541  
2542  	return batch;
2543  }
2544  
nr_pcp_high(struct per_cpu_pages * pcp,struct zone * zone,int batch,bool free_high)2545  static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone,
2546  		       int batch, bool free_high)
2547  {
2548  	int high, high_min, high_max;
2549  
2550  	high_min = READ_ONCE(pcp->high_min);
2551  	high_max = READ_ONCE(pcp->high_max);
2552  	high = pcp->high = clamp(pcp->high, high_min, high_max);
2553  
2554  	if (unlikely(!high))
2555  		return 0;
2556  
2557  	if (unlikely(free_high)) {
2558  		pcp->high = max(high - (batch << CONFIG_PCP_BATCH_SCALE_MAX),
2559  				high_min);
2560  		return 0;
2561  	}
2562  
2563  	/*
2564  	 * If reclaim is active, limit the number of pages that can be
2565  	 * stored on pcp lists
2566  	 */
2567  	if (test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags)) {
2568  		int free_count = max_t(int, pcp->free_count, batch);
2569  
2570  		pcp->high = max(high - free_count, high_min);
2571  		return min(batch << 2, pcp->high);
2572  	}
2573  
2574  	if (high_min == high_max)
2575  		return high;
2576  
2577  	if (test_bit(ZONE_BELOW_HIGH, &zone->flags)) {
2578  		int free_count = max_t(int, pcp->free_count, batch);
2579  
2580  		pcp->high = max(high - free_count, high_min);
2581  		high = max(pcp->count, high_min);
2582  	} else if (pcp->count >= high) {
2583  		int need_high = pcp->free_count + batch;
2584  
2585  		/* pcp->high should be large enough to hold batch freed pages */
2586  		if (pcp->high < need_high)
2587  			pcp->high = clamp(need_high, high_min, high_max);
2588  	}
2589  
2590  	return high;
2591  }
2592  
free_unref_page_commit(struct zone * zone,struct per_cpu_pages * pcp,struct page * page,int migratetype,unsigned int order)2593  static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
2594  				   struct page *page, int migratetype,
2595  				   unsigned int order)
2596  {
2597  	int high, batch;
2598  	int pindex;
2599  	bool free_high = false;
2600  
2601  	/*
2602  	 * On freeing, reduce the number of pages that are batch allocated.
2603  	 * See nr_pcp_alloc() where alloc_factor is increased for subsequent
2604  	 * allocations.
2605  	 */
2606  	pcp->alloc_factor >>= 1;
2607  	__count_vm_events(PGFREE, 1 << order);
2608  	pindex = order_to_pindex(migratetype, order);
2609  	list_add(&page->pcp_list, &pcp->lists[pindex]);
2610  	pcp->count += 1 << order;
2611  
2612  	batch = READ_ONCE(pcp->batch);
2613  	/*
2614  	 * As high-order pages other than THP's stored on PCP can contribute
2615  	 * to fragmentation, limit the number stored when PCP is heavily
2616  	 * freeing without allocation. The remainder after bulk freeing
2617  	 * stops will be drained from vmstat refresh context.
2618  	 */
2619  	if (order && order <= PAGE_ALLOC_COSTLY_ORDER) {
2620  		free_high = (pcp->free_count >= batch &&
2621  			     (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) &&
2622  			     (!(pcp->flags & PCPF_FREE_HIGH_BATCH) ||
2623  			      pcp->count >= READ_ONCE(batch)));
2624  		pcp->flags |= PCPF_PREV_FREE_HIGH_ORDER;
2625  	} else if (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) {
2626  		pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER;
2627  	}
2628  	if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX))
2629  		pcp->free_count += (1 << order);
2630  	high = nr_pcp_high(pcp, zone, batch, free_high);
2631  	if (pcp->count >= high) {
2632  		free_pcppages_bulk(zone, nr_pcp_free(pcp, batch, high, free_high),
2633  				   pcp, pindex);
2634  		if (test_bit(ZONE_BELOW_HIGH, &zone->flags) &&
2635  		    zone_watermark_ok(zone, 0, high_wmark_pages(zone),
2636  				      ZONE_MOVABLE, 0))
2637  			clear_bit(ZONE_BELOW_HIGH, &zone->flags);
2638  	}
2639  }
2640  
2641  /*
2642   * Free a pcp page
2643   */
free_unref_page(struct page * page,unsigned int order)2644  void free_unref_page(struct page *page, unsigned int order)
2645  {
2646  	unsigned long __maybe_unused UP_flags;
2647  	struct per_cpu_pages *pcp;
2648  	struct zone *zone;
2649  	unsigned long pfn = page_to_pfn(page);
2650  	int migratetype;
2651  
2652  	if (!pcp_allowed_order(order)) {
2653  		__free_pages_ok(page, order, FPI_NONE);
2654  		return;
2655  	}
2656  
2657  	if (!free_pages_prepare(page, order))
2658  		return;
2659  
2660  	/*
2661  	 * We only track unmovable, reclaimable and movable on pcp lists.
2662  	 * Place ISOLATE pages on the isolated list because they are being
2663  	 * offlined but treat HIGHATOMIC and CMA as movable pages so we can
2664  	 * get those areas back if necessary. Otherwise, we may have to free
2665  	 * excessively into the page allocator
2666  	 */
2667  	migratetype = get_pfnblock_migratetype(page, pfn);
2668  	if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
2669  		if (unlikely(is_migrate_isolate(migratetype))) {
2670  			free_one_page(page_zone(page), page, pfn, order, FPI_NONE);
2671  			return;
2672  		}
2673  		migratetype = MIGRATE_MOVABLE;
2674  	}
2675  
2676  	zone = page_zone(page);
2677  	pcp_trylock_prepare(UP_flags);
2678  	pcp = pcp_spin_trylock(zone->per_cpu_pageset);
2679  	if (pcp) {
2680  		free_unref_page_commit(zone, pcp, page, migratetype, order);
2681  		pcp_spin_unlock(pcp);
2682  	} else {
2683  		free_one_page(zone, page, pfn, order, FPI_NONE);
2684  	}
2685  	pcp_trylock_finish(UP_flags);
2686  }
2687  
2688  /*
2689   * Free a batch of folios
2690   */
free_unref_folios(struct folio_batch * folios)2691  void free_unref_folios(struct folio_batch *folios)
2692  {
2693  	unsigned long __maybe_unused UP_flags;
2694  	struct per_cpu_pages *pcp = NULL;
2695  	struct zone *locked_zone = NULL;
2696  	int i, j;
2697  
2698  	/* Prepare folios for freeing */
2699  	for (i = 0, j = 0; i < folios->nr; i++) {
2700  		struct folio *folio = folios->folios[i];
2701  		unsigned long pfn = folio_pfn(folio);
2702  		unsigned int order = folio_order(folio);
2703  
2704  		if (!free_pages_prepare(&folio->page, order))
2705  			continue;
2706  		/*
2707  		 * Free orders not handled on the PCP directly to the
2708  		 * allocator.
2709  		 */
2710  		if (!pcp_allowed_order(order)) {
2711  			free_one_page(folio_zone(folio), &folio->page,
2712  				      pfn, order, FPI_NONE);
2713  			continue;
2714  		}
2715  		folio->private = (void *)(unsigned long)order;
2716  		if (j != i)
2717  			folios->folios[j] = folio;
2718  		j++;
2719  	}
2720  	folios->nr = j;
2721  
2722  	for (i = 0; i < folios->nr; i++) {
2723  		struct folio *folio = folios->folios[i];
2724  		struct zone *zone = folio_zone(folio);
2725  		unsigned long pfn = folio_pfn(folio);
2726  		unsigned int order = (unsigned long)folio->private;
2727  		int migratetype;
2728  
2729  		folio->private = NULL;
2730  		migratetype = get_pfnblock_migratetype(&folio->page, pfn);
2731  
2732  		/* Different zone requires a different pcp lock */
2733  		if (zone != locked_zone ||
2734  		    is_migrate_isolate(migratetype)) {
2735  			if (pcp) {
2736  				pcp_spin_unlock(pcp);
2737  				pcp_trylock_finish(UP_flags);
2738  				locked_zone = NULL;
2739  				pcp = NULL;
2740  			}
2741  
2742  			/*
2743  			 * Free isolated pages directly to the
2744  			 * allocator, see comment in free_unref_page.
2745  			 */
2746  			if (is_migrate_isolate(migratetype)) {
2747  				free_one_page(zone, &folio->page, pfn,
2748  					      order, FPI_NONE);
2749  				continue;
2750  			}
2751  
2752  			/*
2753  			 * trylock is necessary as folios may be getting freed
2754  			 * from IRQ or SoftIRQ context after an IO completion.
2755  			 */
2756  			pcp_trylock_prepare(UP_flags);
2757  			pcp = pcp_spin_trylock(zone->per_cpu_pageset);
2758  			if (unlikely(!pcp)) {
2759  				pcp_trylock_finish(UP_flags);
2760  				free_one_page(zone, &folio->page, pfn,
2761  					      order, FPI_NONE);
2762  				continue;
2763  			}
2764  			locked_zone = zone;
2765  		}
2766  
2767  		/*
2768  		 * Non-isolated types over MIGRATE_PCPTYPES get added
2769  		 * to the MIGRATE_MOVABLE pcp list.
2770  		 */
2771  		if (unlikely(migratetype >= MIGRATE_PCPTYPES))
2772  			migratetype = MIGRATE_MOVABLE;
2773  
2774  		trace_mm_page_free_batched(&folio->page);
2775  		free_unref_page_commit(zone, pcp, &folio->page, migratetype,
2776  				order);
2777  	}
2778  
2779  	if (pcp) {
2780  		pcp_spin_unlock(pcp);
2781  		pcp_trylock_finish(UP_flags);
2782  	}
2783  	folio_batch_reinit(folios);
2784  }
2785  
2786  /*
2787   * split_page takes a non-compound higher-order page, and splits it into
2788   * n (1<<order) sub-pages: page[0..n]
2789   * Each sub-page must be freed individually.
2790   *
2791   * Note: this is probably too low level an operation for use in drivers.
2792   * Please consult with lkml before using this in your driver.
2793   */
split_page(struct page * page,unsigned int order)2794  void split_page(struct page *page, unsigned int order)
2795  {
2796  	int i;
2797  
2798  	VM_BUG_ON_PAGE(PageCompound(page), page);
2799  	VM_BUG_ON_PAGE(!page_count(page), page);
2800  
2801  	for (i = 1; i < (1 << order); i++)
2802  		set_page_refcounted(page + i);
2803  	split_page_owner(page, order, 0);
2804  	pgalloc_tag_split(page_folio(page), order, 0);
2805  	split_page_memcg(page, order, 0);
2806  }
2807  EXPORT_SYMBOL_GPL(split_page);
2808  
__isolate_free_page(struct page * page,unsigned int order)2809  int __isolate_free_page(struct page *page, unsigned int order)
2810  {
2811  	struct zone *zone = page_zone(page);
2812  	int mt = get_pageblock_migratetype(page);
2813  
2814  	if (!is_migrate_isolate(mt)) {
2815  		unsigned long watermark;
2816  		/*
2817  		 * Obey watermarks as if the page was being allocated. We can
2818  		 * emulate a high-order watermark check with a raised order-0
2819  		 * watermark, because we already know our high-order page
2820  		 * exists.
2821  		 */
2822  		watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
2823  		if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
2824  			return 0;
2825  	}
2826  
2827  	del_page_from_free_list(page, zone, order, mt);
2828  
2829  	/*
2830  	 * Set the pageblock if the isolated page is at least half of a
2831  	 * pageblock
2832  	 */
2833  	if (order >= pageblock_order - 1) {
2834  		struct page *endpage = page + (1 << order) - 1;
2835  		for (; page < endpage; page += pageblock_nr_pages) {
2836  			int mt = get_pageblock_migratetype(page);
2837  			/*
2838  			 * Only change normal pageblocks (i.e., they can merge
2839  			 * with others)
2840  			 */
2841  			if (migratetype_is_mergeable(mt))
2842  				move_freepages_block(zone, page, mt,
2843  						     MIGRATE_MOVABLE);
2844  		}
2845  	}
2846  
2847  	return 1UL << order;
2848  }
2849  
2850  /**
2851   * __putback_isolated_page - Return a now-isolated page back where we got it
2852   * @page: Page that was isolated
2853   * @order: Order of the isolated page
2854   * @mt: The page's pageblock's migratetype
2855   *
2856   * This function is meant to return a page pulled from the free lists via
2857   * __isolate_free_page back to the free lists they were pulled from.
2858   */
__putback_isolated_page(struct page * page,unsigned int order,int mt)2859  void __putback_isolated_page(struct page *page, unsigned int order, int mt)
2860  {
2861  	struct zone *zone = page_zone(page);
2862  
2863  	/* zone lock should be held when this function is called */
2864  	lockdep_assert_held(&zone->lock);
2865  
2866  	/* Return isolated page to tail of freelist. */
2867  	__free_one_page(page, page_to_pfn(page), zone, order, mt,
2868  			FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
2869  }
2870  
2871  /*
2872   * Update NUMA hit/miss statistics
2873   */
zone_statistics(struct zone * preferred_zone,struct zone * z,long nr_account)2874  static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
2875  				   long nr_account)
2876  {
2877  #ifdef CONFIG_NUMA
2878  	enum numa_stat_item local_stat = NUMA_LOCAL;
2879  
2880  	/* skip numa counters update if numa stats is disabled */
2881  	if (!static_branch_likely(&vm_numa_stat_key))
2882  		return;
2883  
2884  	if (zone_to_nid(z) != numa_node_id())
2885  		local_stat = NUMA_OTHER;
2886  
2887  	if (zone_to_nid(z) == zone_to_nid(preferred_zone))
2888  		__count_numa_events(z, NUMA_HIT, nr_account);
2889  	else {
2890  		__count_numa_events(z, NUMA_MISS, nr_account);
2891  		__count_numa_events(preferred_zone, NUMA_FOREIGN, nr_account);
2892  	}
2893  	__count_numa_events(z, local_stat, nr_account);
2894  #endif
2895  }
2896  
2897  static __always_inline
rmqueue_buddy(struct zone * preferred_zone,struct zone * zone,unsigned int order,unsigned int alloc_flags,int migratetype)2898  struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone,
2899  			   unsigned int order, unsigned int alloc_flags,
2900  			   int migratetype)
2901  {
2902  	struct page *page;
2903  	unsigned long flags;
2904  
2905  	do {
2906  		page = NULL;
2907  		spin_lock_irqsave(&zone->lock, flags);
2908  		if (alloc_flags & ALLOC_HIGHATOMIC)
2909  			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
2910  		if (!page) {
2911  			page = __rmqueue(zone, order, migratetype, alloc_flags);
2912  
2913  			/*
2914  			 * If the allocation fails, allow OOM handling and
2915  			 * order-0 (atomic) allocs access to HIGHATOMIC
2916  			 * reserves as failing now is worse than failing a
2917  			 * high-order atomic allocation in the future.
2918  			 */
2919  			if (!page && (alloc_flags & (ALLOC_OOM|ALLOC_NON_BLOCK)))
2920  				page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
2921  
2922  			if (!page) {
2923  				spin_unlock_irqrestore(&zone->lock, flags);
2924  				return NULL;
2925  			}
2926  		}
2927  		spin_unlock_irqrestore(&zone->lock, flags);
2928  	} while (check_new_pages(page, order));
2929  
2930  	__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
2931  	zone_statistics(preferred_zone, zone, 1);
2932  
2933  	return page;
2934  }
2935  
nr_pcp_alloc(struct per_cpu_pages * pcp,struct zone * zone,int order)2936  static int nr_pcp_alloc(struct per_cpu_pages *pcp, struct zone *zone, int order)
2937  {
2938  	int high, base_batch, batch, max_nr_alloc;
2939  	int high_max, high_min;
2940  
2941  	base_batch = READ_ONCE(pcp->batch);
2942  	high_min = READ_ONCE(pcp->high_min);
2943  	high_max = READ_ONCE(pcp->high_max);
2944  	high = pcp->high = clamp(pcp->high, high_min, high_max);
2945  
2946  	/* Check for PCP disabled or boot pageset */
2947  	if (unlikely(high < base_batch))
2948  		return 1;
2949  
2950  	if (order)
2951  		batch = base_batch;
2952  	else
2953  		batch = (base_batch << pcp->alloc_factor);
2954  
2955  	/*
2956  	 * If we had larger pcp->high, we could avoid to allocate from
2957  	 * zone.
2958  	 */
2959  	if (high_min != high_max && !test_bit(ZONE_BELOW_HIGH, &zone->flags))
2960  		high = pcp->high = min(high + batch, high_max);
2961  
2962  	if (!order) {
2963  		max_nr_alloc = max(high - pcp->count - base_batch, base_batch);
2964  		/*
2965  		 * Double the number of pages allocated each time there is
2966  		 * subsequent allocation of order-0 pages without any freeing.
2967  		 */
2968  		if (batch <= max_nr_alloc &&
2969  		    pcp->alloc_factor < CONFIG_PCP_BATCH_SCALE_MAX)
2970  			pcp->alloc_factor++;
2971  		batch = min(batch, max_nr_alloc);
2972  	}
2973  
2974  	/*
2975  	 * Scale batch relative to order if batch implies free pages
2976  	 * can be stored on the PCP. Batch can be 1 for small zones or
2977  	 * for boot pagesets which should never store free pages as
2978  	 * the pages may belong to arbitrary zones.
2979  	 */
2980  	if (batch > 1)
2981  		batch = max(batch >> order, 2);
2982  
2983  	return batch;
2984  }
2985  
2986  /* Remove page from the per-cpu list, caller must protect the list */
2987  static inline
__rmqueue_pcplist(struct zone * zone,unsigned int order,int migratetype,unsigned int alloc_flags,struct per_cpu_pages * pcp,struct list_head * list)2988  struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
2989  			int migratetype,
2990  			unsigned int alloc_flags,
2991  			struct per_cpu_pages *pcp,
2992  			struct list_head *list)
2993  {
2994  	struct page *page;
2995  
2996  	do {
2997  		if (list_empty(list)) {
2998  			int batch = nr_pcp_alloc(pcp, zone, order);
2999  			int alloced;
3000  
3001  			alloced = rmqueue_bulk(zone, order,
3002  					batch, list,
3003  					migratetype, alloc_flags);
3004  
3005  			pcp->count += alloced << order;
3006  			if (unlikely(list_empty(list)))
3007  				return NULL;
3008  		}
3009  
3010  		page = list_first_entry(list, struct page, pcp_list);
3011  		list_del(&page->pcp_list);
3012  		pcp->count -= 1 << order;
3013  	} while (check_new_pages(page, order));
3014  
3015  	return page;
3016  }
3017  
3018  /* Lock and remove page from the per-cpu list */
rmqueue_pcplist(struct zone * preferred_zone,struct zone * zone,unsigned int order,int migratetype,unsigned int alloc_flags)3019  static struct page *rmqueue_pcplist(struct zone *preferred_zone,
3020  			struct zone *zone, unsigned int order,
3021  			int migratetype, unsigned int alloc_flags)
3022  {
3023  	struct per_cpu_pages *pcp;
3024  	struct list_head *list;
3025  	struct page *page;
3026  	unsigned long __maybe_unused UP_flags;
3027  
3028  	/* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */
3029  	pcp_trylock_prepare(UP_flags);
3030  	pcp = pcp_spin_trylock(zone->per_cpu_pageset);
3031  	if (!pcp) {
3032  		pcp_trylock_finish(UP_flags);
3033  		return NULL;
3034  	}
3035  
3036  	/*
3037  	 * On allocation, reduce the number of pages that are batch freed.
3038  	 * See nr_pcp_free() where free_factor is increased for subsequent
3039  	 * frees.
3040  	 */
3041  	pcp->free_count >>= 1;
3042  	list = &pcp->lists[order_to_pindex(migratetype, order)];
3043  	page = __rmqueue_pcplist(zone, order, migratetype, alloc_flags, pcp, list);
3044  	pcp_spin_unlock(pcp);
3045  	pcp_trylock_finish(UP_flags);
3046  	if (page) {
3047  		__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
3048  		zone_statistics(preferred_zone, zone, 1);
3049  	}
3050  	return page;
3051  }
3052  
3053  /*
3054   * Allocate a page from the given zone.
3055   * Use pcplists for THP or "cheap" high-order allocations.
3056   */
3057  
3058  /*
3059   * Do not instrument rmqueue() with KMSAN. This function may call
3060   * __msan_poison_alloca() through a call to set_pfnblock_flags_mask().
3061   * If __msan_poison_alloca() attempts to allocate pages for the stack depot, it
3062   * may call rmqueue() again, which will result in a deadlock.
3063   */
3064  __no_sanitize_memory
3065  static inline
rmqueue(struct zone * preferred_zone,struct zone * zone,unsigned int order,gfp_t gfp_flags,unsigned int alloc_flags,int migratetype)3066  struct page *rmqueue(struct zone *preferred_zone,
3067  			struct zone *zone, unsigned int order,
3068  			gfp_t gfp_flags, unsigned int alloc_flags,
3069  			int migratetype)
3070  {
3071  	struct page *page;
3072  
3073  	if (likely(pcp_allowed_order(order))) {
3074  		page = rmqueue_pcplist(preferred_zone, zone, order,
3075  				       migratetype, alloc_flags);
3076  		if (likely(page))
3077  			goto out;
3078  	}
3079  
3080  	page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,
3081  							migratetype);
3082  
3083  out:
3084  	/* Separate test+clear to avoid unnecessary atomics */
3085  	if ((alloc_flags & ALLOC_KSWAPD) &&
3086  	    unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
3087  		clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
3088  		wakeup_kswapd(zone, 0, 0, zone_idx(zone));
3089  	}
3090  
3091  	VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
3092  	return page;
3093  }
3094  
__zone_watermark_unusable_free(struct zone * z,unsigned int order,unsigned int alloc_flags)3095  static inline long __zone_watermark_unusable_free(struct zone *z,
3096  				unsigned int order, unsigned int alloc_flags)
3097  {
3098  	long unusable_free = (1 << order) - 1;
3099  
3100  	/*
3101  	 * If the caller does not have rights to reserves below the min
3102  	 * watermark then subtract the free pages reserved for highatomic.
3103  	 */
3104  	if (likely(!(alloc_flags & ALLOC_RESERVES)))
3105  		unusable_free += READ_ONCE(z->nr_free_highatomic);
3106  
3107  #ifdef CONFIG_CMA
3108  	/* If allocation can't use CMA areas don't use free CMA pages */
3109  	if (!(alloc_flags & ALLOC_CMA))
3110  		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
3111  #endif
3112  
3113  	return unusable_free;
3114  }
3115  
3116  /*
3117   * Return true if free base pages are above 'mark'. For high-order checks it
3118   * will return true of the order-0 watermark is reached and there is at least
3119   * one free page of a suitable size. Checking now avoids taking the zone lock
3120   * to check in the allocation paths if no pages are free.
3121   */
__zone_watermark_ok(struct zone * z,unsigned int order,unsigned long mark,int highest_zoneidx,unsigned int alloc_flags,long free_pages)3122  bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
3123  			 int highest_zoneidx, unsigned int alloc_flags,
3124  			 long free_pages)
3125  {
3126  	long min = mark;
3127  	int o;
3128  
3129  	/* free_pages may go negative - that's OK */
3130  	free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
3131  
3132  	if (unlikely(alloc_flags & ALLOC_RESERVES)) {
3133  		/*
3134  		 * __GFP_HIGH allows access to 50% of the min reserve as well
3135  		 * as OOM.
3136  		 */
3137  		if (alloc_flags & ALLOC_MIN_RESERVE) {
3138  			min -= min / 2;
3139  
3140  			/*
3141  			 * Non-blocking allocations (e.g. GFP_ATOMIC) can
3142  			 * access more reserves than just __GFP_HIGH. Other
3143  			 * non-blocking allocations requests such as GFP_NOWAIT
3144  			 * or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get
3145  			 * access to the min reserve.
3146  			 */
3147  			if (alloc_flags & ALLOC_NON_BLOCK)
3148  				min -= min / 4;
3149  		}
3150  
3151  		/*
3152  		 * OOM victims can try even harder than the normal reserve
3153  		 * users on the grounds that it's definitely going to be in
3154  		 * the exit path shortly and free memory. Any allocation it
3155  		 * makes during the free path will be small and short-lived.
3156  		 */
3157  		if (alloc_flags & ALLOC_OOM)
3158  			min -= min / 2;
3159  	}
3160  
3161  	/*
3162  	 * Check watermarks for an order-0 allocation request. If these
3163  	 * are not met, then a high-order request also cannot go ahead
3164  	 * even if a suitable page happened to be free.
3165  	 */
3166  	if (free_pages <= min + z->lowmem_reserve[highest_zoneidx])
3167  		return false;
3168  
3169  	/* If this is an order-0 request then the watermark is fine */
3170  	if (!order)
3171  		return true;
3172  
3173  	/* For a high-order request, check at least one suitable page is free */
3174  	for (o = order; o < NR_PAGE_ORDERS; o++) {
3175  		struct free_area *area = &z->free_area[o];
3176  		int mt;
3177  
3178  		if (!area->nr_free)
3179  			continue;
3180  
3181  		for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
3182  			if (!free_area_empty(area, mt))
3183  				return true;
3184  		}
3185  
3186  #ifdef CONFIG_CMA
3187  		if ((alloc_flags & ALLOC_CMA) &&
3188  		    !free_area_empty(area, MIGRATE_CMA)) {
3189  			return true;
3190  		}
3191  #endif
3192  		if ((alloc_flags & (ALLOC_HIGHATOMIC|ALLOC_OOM)) &&
3193  		    !free_area_empty(area, MIGRATE_HIGHATOMIC)) {
3194  			return true;
3195  		}
3196  	}
3197  	return false;
3198  }
3199  
zone_watermark_ok(struct zone * z,unsigned int order,unsigned long mark,int highest_zoneidx,unsigned int alloc_flags)3200  bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
3201  		      int highest_zoneidx, unsigned int alloc_flags)
3202  {
3203  	return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
3204  					zone_page_state(z, NR_FREE_PAGES));
3205  }
3206  
zone_watermark_fast(struct zone * z,unsigned int order,unsigned long mark,int highest_zoneidx,unsigned int alloc_flags,gfp_t gfp_mask)3207  static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
3208  				unsigned long mark, int highest_zoneidx,
3209  				unsigned int alloc_flags, gfp_t gfp_mask)
3210  {
3211  	long free_pages;
3212  
3213  	free_pages = zone_page_state(z, NR_FREE_PAGES);
3214  
3215  	/*
3216  	 * Fast check for order-0 only. If this fails then the reserves
3217  	 * need to be calculated.
3218  	 */
3219  	if (!order) {
3220  		long usable_free;
3221  		long reserved;
3222  
3223  		usable_free = free_pages;
3224  		reserved = __zone_watermark_unusable_free(z, 0, alloc_flags);
3225  
3226  		/* reserved may over estimate high-atomic reserves. */
3227  		usable_free -= min(usable_free, reserved);
3228  		if (usable_free > mark + z->lowmem_reserve[highest_zoneidx])
3229  			return true;
3230  	}
3231  
3232  	if (__zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
3233  					free_pages))
3234  		return true;
3235  
3236  	/*
3237  	 * Ignore watermark boosting for __GFP_HIGH order-0 allocations
3238  	 * when checking the min watermark. The min watermark is the
3239  	 * point where boosting is ignored so that kswapd is woken up
3240  	 * when below the low watermark.
3241  	 */
3242  	if (unlikely(!order && (alloc_flags & ALLOC_MIN_RESERVE) && z->watermark_boost
3243  		&& ((alloc_flags & ALLOC_WMARK_MASK) == WMARK_MIN))) {
3244  		mark = z->_watermark[WMARK_MIN];
3245  		return __zone_watermark_ok(z, order, mark, highest_zoneidx,
3246  					alloc_flags, free_pages);
3247  	}
3248  
3249  	return false;
3250  }
3251  
zone_watermark_ok_safe(struct zone * z,unsigned int order,unsigned long mark,int highest_zoneidx)3252  bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
3253  			unsigned long mark, int highest_zoneidx)
3254  {
3255  	long free_pages = zone_page_state(z, NR_FREE_PAGES);
3256  
3257  	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
3258  		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
3259  
3260  	return __zone_watermark_ok(z, order, mark, highest_zoneidx, 0,
3261  								free_pages);
3262  }
3263  
3264  #ifdef CONFIG_NUMA
3265  int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE;
3266  
zone_allows_reclaim(struct zone * local_zone,struct zone * zone)3267  static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
3268  {
3269  	return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
3270  				node_reclaim_distance;
3271  }
3272  #else	/* CONFIG_NUMA */
zone_allows_reclaim(struct zone * local_zone,struct zone * zone)3273  static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
3274  {
3275  	return true;
3276  }
3277  #endif	/* CONFIG_NUMA */
3278  
3279  /*
3280   * The restriction on ZONE_DMA32 as being a suitable zone to use to avoid
3281   * fragmentation is subtle. If the preferred zone was HIGHMEM then
3282   * premature use of a lower zone may cause lowmem pressure problems that
3283   * are worse than fragmentation. If the next zone is ZONE_DMA then it is
3284   * probably too small. It only makes sense to spread allocations to avoid
3285   * fragmentation between the Normal and DMA32 zones.
3286   */
3287  static inline unsigned int
alloc_flags_nofragment(struct zone * zone,gfp_t gfp_mask)3288  alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
3289  {
3290  	unsigned int alloc_flags;
3291  
3292  	/*
3293  	 * __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
3294  	 * to save a branch.
3295  	 */
3296  	alloc_flags = (__force int) (gfp_mask & __GFP_KSWAPD_RECLAIM);
3297  
3298  #ifdef CONFIG_ZONE_DMA32
3299  	if (!zone)
3300  		return alloc_flags;
3301  
3302  	if (zone_idx(zone) != ZONE_NORMAL)
3303  		return alloc_flags;
3304  
3305  	/*
3306  	 * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
3307  	 * the pointer is within zone->zone_pgdat->node_zones[]. Also assume
3308  	 * on UMA that if Normal is populated then so is DMA32.
3309  	 */
3310  	BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
3311  	if (nr_online_nodes > 1 && !populated_zone(--zone))
3312  		return alloc_flags;
3313  
3314  	alloc_flags |= ALLOC_NOFRAGMENT;
3315  #endif /* CONFIG_ZONE_DMA32 */
3316  	return alloc_flags;
3317  }
3318  
3319  /* Must be called after current_gfp_context() which can change gfp_mask */
gfp_to_alloc_flags_cma(gfp_t gfp_mask,unsigned int alloc_flags)3320  static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
3321  						  unsigned int alloc_flags)
3322  {
3323  #ifdef CONFIG_CMA
3324  	if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
3325  		alloc_flags |= ALLOC_CMA;
3326  #endif
3327  	return alloc_flags;
3328  }
3329  
3330  /*
3331   * get_page_from_freelist goes through the zonelist trying to allocate
3332   * a page.
3333   */
3334  static struct page *
get_page_from_freelist(gfp_t gfp_mask,unsigned int order,int alloc_flags,const struct alloc_context * ac)3335  get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
3336  						const struct alloc_context *ac)
3337  {
3338  	struct zoneref *z;
3339  	struct zone *zone;
3340  	struct pglist_data *last_pgdat = NULL;
3341  	bool last_pgdat_dirty_ok = false;
3342  	bool no_fallback;
3343  
3344  retry:
3345  	/*
3346  	 * Scan zonelist, looking for a zone with enough free.
3347  	 * See also cpuset_node_allowed() comment in kernel/cgroup/cpuset.c.
3348  	 */
3349  	no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
3350  	z = ac->preferred_zoneref;
3351  	for_next_zone_zonelist_nodemask(zone, z, ac->highest_zoneidx,
3352  					ac->nodemask) {
3353  		struct page *page;
3354  		unsigned long mark;
3355  
3356  		if (cpusets_enabled() &&
3357  			(alloc_flags & ALLOC_CPUSET) &&
3358  			!__cpuset_zone_allowed(zone, gfp_mask))
3359  				continue;
3360  		/*
3361  		 * When allocating a page cache page for writing, we
3362  		 * want to get it from a node that is within its dirty
3363  		 * limit, such that no single node holds more than its
3364  		 * proportional share of globally allowed dirty pages.
3365  		 * The dirty limits take into account the node's
3366  		 * lowmem reserves and high watermark so that kswapd
3367  		 * should be able to balance it without having to
3368  		 * write pages from its LRU list.
3369  		 *
3370  		 * XXX: For now, allow allocations to potentially
3371  		 * exceed the per-node dirty limit in the slowpath
3372  		 * (spread_dirty_pages unset) before going into reclaim,
3373  		 * which is important when on a NUMA setup the allowed
3374  		 * nodes are together not big enough to reach the
3375  		 * global limit.  The proper fix for these situations
3376  		 * will require awareness of nodes in the
3377  		 * dirty-throttling and the flusher threads.
3378  		 */
3379  		if (ac->spread_dirty_pages) {
3380  			if (last_pgdat != zone->zone_pgdat) {
3381  				last_pgdat = zone->zone_pgdat;
3382  				last_pgdat_dirty_ok = node_dirty_ok(zone->zone_pgdat);
3383  			}
3384  
3385  			if (!last_pgdat_dirty_ok)
3386  				continue;
3387  		}
3388  
3389  		if (no_fallback && nr_online_nodes > 1 &&
3390  		    zone != zonelist_zone(ac->preferred_zoneref)) {
3391  			int local_nid;
3392  
3393  			/*
3394  			 * If moving to a remote node, retry but allow
3395  			 * fragmenting fallbacks. Locality is more important
3396  			 * than fragmentation avoidance.
3397  			 */
3398  			local_nid = zonelist_node_idx(ac->preferred_zoneref);
3399  			if (zone_to_nid(zone) != local_nid) {
3400  				alloc_flags &= ~ALLOC_NOFRAGMENT;
3401  				goto retry;
3402  			}
3403  		}
3404  
3405  		cond_accept_memory(zone, order);
3406  
3407  		/*
3408  		 * Detect whether the number of free pages is below high
3409  		 * watermark.  If so, we will decrease pcp->high and free
3410  		 * PCP pages in free path to reduce the possibility of
3411  		 * premature page reclaiming.  Detection is done here to
3412  		 * avoid to do that in hotter free path.
3413  		 */
3414  		if (test_bit(ZONE_BELOW_HIGH, &zone->flags))
3415  			goto check_alloc_wmark;
3416  
3417  		mark = high_wmark_pages(zone);
3418  		if (zone_watermark_fast(zone, order, mark,
3419  					ac->highest_zoneidx, alloc_flags,
3420  					gfp_mask))
3421  			goto try_this_zone;
3422  		else
3423  			set_bit(ZONE_BELOW_HIGH, &zone->flags);
3424  
3425  check_alloc_wmark:
3426  		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
3427  		if (!zone_watermark_fast(zone, order, mark,
3428  				       ac->highest_zoneidx, alloc_flags,
3429  				       gfp_mask)) {
3430  			int ret;
3431  
3432  			if (cond_accept_memory(zone, order))
3433  				goto try_this_zone;
3434  
3435  			/*
3436  			 * Watermark failed for this zone, but see if we can
3437  			 * grow this zone if it contains deferred pages.
3438  			 */
3439  			if (deferred_pages_enabled()) {
3440  				if (_deferred_grow_zone(zone, order))
3441  					goto try_this_zone;
3442  			}
3443  			/* Checked here to keep the fast path fast */
3444  			BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
3445  			if (alloc_flags & ALLOC_NO_WATERMARKS)
3446  				goto try_this_zone;
3447  
3448  			if (!node_reclaim_enabled() ||
3449  			    !zone_allows_reclaim(zonelist_zone(ac->preferred_zoneref), zone))
3450  				continue;
3451  
3452  			ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
3453  			switch (ret) {
3454  			case NODE_RECLAIM_NOSCAN:
3455  				/* did not scan */
3456  				continue;
3457  			case NODE_RECLAIM_FULL:
3458  				/* scanned but unreclaimable */
3459  				continue;
3460  			default:
3461  				/* did we reclaim enough */
3462  				if (zone_watermark_ok(zone, order, mark,
3463  					ac->highest_zoneidx, alloc_flags))
3464  					goto try_this_zone;
3465  
3466  				continue;
3467  			}
3468  		}
3469  
3470  try_this_zone:
3471  		page = rmqueue(zonelist_zone(ac->preferred_zoneref), zone, order,
3472  				gfp_mask, alloc_flags, ac->migratetype);
3473  		if (page) {
3474  			prep_new_page(page, order, gfp_mask, alloc_flags);
3475  
3476  			/*
3477  			 * If this is a high-order atomic allocation then check
3478  			 * if the pageblock should be reserved for the future
3479  			 */
3480  			if (unlikely(alloc_flags & ALLOC_HIGHATOMIC))
3481  				reserve_highatomic_pageblock(page, order, zone);
3482  
3483  			return page;
3484  		} else {
3485  			if (cond_accept_memory(zone, order))
3486  				goto try_this_zone;
3487  
3488  			/* Try again if zone has deferred pages */
3489  			if (deferred_pages_enabled()) {
3490  				if (_deferred_grow_zone(zone, order))
3491  					goto try_this_zone;
3492  			}
3493  		}
3494  	}
3495  
3496  	/*
3497  	 * It's possible on a UMA machine to get through all zones that are
3498  	 * fragmented. If avoiding fragmentation, reset and try again.
3499  	 */
3500  	if (no_fallback) {
3501  		alloc_flags &= ~ALLOC_NOFRAGMENT;
3502  		goto retry;
3503  	}
3504  
3505  	return NULL;
3506  }
3507  
warn_alloc_show_mem(gfp_t gfp_mask,nodemask_t * nodemask)3508  static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
3509  {
3510  	unsigned int filter = SHOW_MEM_FILTER_NODES;
3511  
3512  	/*
3513  	 * This documents exceptions given to allocations in certain
3514  	 * contexts that are allowed to allocate outside current's set
3515  	 * of allowed nodes.
3516  	 */
3517  	if (!(gfp_mask & __GFP_NOMEMALLOC))
3518  		if (tsk_is_oom_victim(current) ||
3519  		    (current->flags & (PF_MEMALLOC | PF_EXITING)))
3520  			filter &= ~SHOW_MEM_FILTER_NODES;
3521  	if (!in_task() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
3522  		filter &= ~SHOW_MEM_FILTER_NODES;
3523  
3524  	__show_mem(filter, nodemask, gfp_zone(gfp_mask));
3525  }
3526  
warn_alloc(gfp_t gfp_mask,nodemask_t * nodemask,const char * fmt,...)3527  void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
3528  {
3529  	struct va_format vaf;
3530  	va_list args;
3531  	static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);
3532  
3533  	if ((gfp_mask & __GFP_NOWARN) ||
3534  	     !__ratelimit(&nopage_rs) ||
3535  	     ((gfp_mask & __GFP_DMA) && !has_managed_dma()))
3536  		return;
3537  
3538  	va_start(args, fmt);
3539  	vaf.fmt = fmt;
3540  	vaf.va = &args;
3541  	pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
3542  			current->comm, &vaf, gfp_mask, &gfp_mask,
3543  			nodemask_pr_args(nodemask));
3544  	va_end(args);
3545  
3546  	cpuset_print_current_mems_allowed();
3547  	pr_cont("\n");
3548  	dump_stack();
3549  	warn_alloc_show_mem(gfp_mask, nodemask);
3550  }
3551  
3552  static inline struct page *
__alloc_pages_cpuset_fallback(gfp_t gfp_mask,unsigned int order,unsigned int alloc_flags,const struct alloc_context * ac)3553  __alloc_pages_cpuset_fallback(gfp_t gfp_mask, unsigned int order,
3554  			      unsigned int alloc_flags,
3555  			      const struct alloc_context *ac)
3556  {
3557  	struct page *page;
3558  
3559  	page = get_page_from_freelist(gfp_mask, order,
3560  			alloc_flags|ALLOC_CPUSET, ac);
3561  	/*
3562  	 * fallback to ignore cpuset restriction if our nodes
3563  	 * are depleted
3564  	 */
3565  	if (!page)
3566  		page = get_page_from_freelist(gfp_mask, order,
3567  				alloc_flags, ac);
3568  
3569  	return page;
3570  }
3571  
3572  static inline struct page *
__alloc_pages_may_oom(gfp_t gfp_mask,unsigned int order,const struct alloc_context * ac,unsigned long * did_some_progress)3573  __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
3574  	const struct alloc_context *ac, unsigned long *did_some_progress)
3575  {
3576  	struct oom_control oc = {
3577  		.zonelist = ac->zonelist,
3578  		.nodemask = ac->nodemask,
3579  		.memcg = NULL,
3580  		.gfp_mask = gfp_mask,
3581  		.order = order,
3582  	};
3583  	struct page *page;
3584  
3585  	*did_some_progress = 0;
3586  
3587  	/*
3588  	 * Acquire the oom lock.  If that fails, somebody else is
3589  	 * making progress for us.
3590  	 */
3591  	if (!mutex_trylock(&oom_lock)) {
3592  		*did_some_progress = 1;
3593  		schedule_timeout_uninterruptible(1);
3594  		return NULL;
3595  	}
3596  
3597  	/*
3598  	 * Go through the zonelist yet one more time, keep very high watermark
3599  	 * here, this is only to catch a parallel oom killing, we must fail if
3600  	 * we're still under heavy pressure. But make sure that this reclaim
3601  	 * attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
3602  	 * allocation which will never fail due to oom_lock already held.
3603  	 */
3604  	page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
3605  				      ~__GFP_DIRECT_RECLAIM, order,
3606  				      ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
3607  	if (page)
3608  		goto out;
3609  
3610  	/* Coredumps can quickly deplete all memory reserves */
3611  	if (current->flags & PF_DUMPCORE)
3612  		goto out;
3613  	/* The OOM killer will not help higher order allocs */
3614  	if (order > PAGE_ALLOC_COSTLY_ORDER)
3615  		goto out;
3616  	/*
3617  	 * We have already exhausted all our reclaim opportunities without any
3618  	 * success so it is time to admit defeat. We will skip the OOM killer
3619  	 * because it is very likely that the caller has a more reasonable
3620  	 * fallback than shooting a random task.
3621  	 *
3622  	 * The OOM killer may not free memory on a specific node.
3623  	 */
3624  	if (gfp_mask & (__GFP_RETRY_MAYFAIL | __GFP_THISNODE))
3625  		goto out;
3626  	/* The OOM killer does not needlessly kill tasks for lowmem */
3627  	if (ac->highest_zoneidx < ZONE_NORMAL)
3628  		goto out;
3629  	if (pm_suspended_storage())
3630  		goto out;
3631  	/*
3632  	 * XXX: GFP_NOFS allocations should rather fail than rely on
3633  	 * other request to make a forward progress.
3634  	 * We are in an unfortunate situation where out_of_memory cannot
3635  	 * do much for this context but let's try it to at least get
3636  	 * access to memory reserved if the current task is killed (see
3637  	 * out_of_memory). Once filesystems are ready to handle allocation
3638  	 * failures more gracefully we should just bail out here.
3639  	 */
3640  
3641  	/* Exhausted what can be done so it's blame time */
3642  	if (out_of_memory(&oc) ||
3643  	    WARN_ON_ONCE_GFP(gfp_mask & __GFP_NOFAIL, gfp_mask)) {
3644  		*did_some_progress = 1;
3645  
3646  		/*
3647  		 * Help non-failing allocations by giving them access to memory
3648  		 * reserves
3649  		 */
3650  		if (gfp_mask & __GFP_NOFAIL)
3651  			page = __alloc_pages_cpuset_fallback(gfp_mask, order,
3652  					ALLOC_NO_WATERMARKS, ac);
3653  	}
3654  out:
3655  	mutex_unlock(&oom_lock);
3656  	return page;
3657  }
3658  
3659  /*
3660   * Maximum number of compaction retries with a progress before OOM
3661   * killer is consider as the only way to move forward.
3662   */
3663  #define MAX_COMPACT_RETRIES 16
3664  
3665  #ifdef CONFIG_COMPACTION
3666  /* Try memory compaction for high-order allocations before reclaim */
3667  static struct page *
__alloc_pages_direct_compact(gfp_t gfp_mask,unsigned int order,unsigned int alloc_flags,const struct alloc_context * ac,enum compact_priority prio,enum compact_result * compact_result)3668  __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
3669  		unsigned int alloc_flags, const struct alloc_context *ac,
3670  		enum compact_priority prio, enum compact_result *compact_result)
3671  {
3672  	struct page *page = NULL;
3673  	unsigned long pflags;
3674  	unsigned int noreclaim_flag;
3675  
3676  	if (!order)
3677  		return NULL;
3678  
3679  	psi_memstall_enter(&pflags);
3680  	delayacct_compact_start();
3681  	noreclaim_flag = memalloc_noreclaim_save();
3682  
3683  	*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
3684  								prio, &page);
3685  
3686  	memalloc_noreclaim_restore(noreclaim_flag);
3687  	psi_memstall_leave(&pflags);
3688  	delayacct_compact_end();
3689  
3690  	if (*compact_result == COMPACT_SKIPPED)
3691  		return NULL;
3692  	/*
3693  	 * At least in one zone compaction wasn't deferred or skipped, so let's
3694  	 * count a compaction stall
3695  	 */
3696  	count_vm_event(COMPACTSTALL);
3697  
3698  	/* Prep a captured page if available */
3699  	if (page)
3700  		prep_new_page(page, order, gfp_mask, alloc_flags);
3701  
3702  	/* Try get a page from the freelist if available */
3703  	if (!page)
3704  		page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
3705  
3706  	if (page) {
3707  		struct zone *zone = page_zone(page);
3708  
3709  		zone->compact_blockskip_flush = false;
3710  		compaction_defer_reset(zone, order, true);
3711  		count_vm_event(COMPACTSUCCESS);
3712  		return page;
3713  	}
3714  
3715  	/*
3716  	 * It's bad if compaction run occurs and fails. The most likely reason
3717  	 * is that pages exist, but not enough to satisfy watermarks.
3718  	 */
3719  	count_vm_event(COMPACTFAIL);
3720  
3721  	cond_resched();
3722  
3723  	return NULL;
3724  }
3725  
3726  static inline bool
should_compact_retry(struct alloc_context * ac,int order,int alloc_flags,enum compact_result compact_result,enum compact_priority * compact_priority,int * compaction_retries)3727  should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
3728  		     enum compact_result compact_result,
3729  		     enum compact_priority *compact_priority,
3730  		     int *compaction_retries)
3731  {
3732  	int max_retries = MAX_COMPACT_RETRIES;
3733  	int min_priority;
3734  	bool ret = false;
3735  	int retries = *compaction_retries;
3736  	enum compact_priority priority = *compact_priority;
3737  
3738  	if (!order)
3739  		return false;
3740  
3741  	if (fatal_signal_pending(current))
3742  		return false;
3743  
3744  	/*
3745  	 * Compaction was skipped due to a lack of free order-0
3746  	 * migration targets. Continue if reclaim can help.
3747  	 */
3748  	if (compact_result == COMPACT_SKIPPED) {
3749  		ret = compaction_zonelist_suitable(ac, order, alloc_flags);
3750  		goto out;
3751  	}
3752  
3753  	/*
3754  	 * Compaction managed to coalesce some page blocks, but the
3755  	 * allocation failed presumably due to a race. Retry some.
3756  	 */
3757  	if (compact_result == COMPACT_SUCCESS) {
3758  		/*
3759  		 * !costly requests are much more important than
3760  		 * __GFP_RETRY_MAYFAIL costly ones because they are de
3761  		 * facto nofail and invoke OOM killer to move on while
3762  		 * costly can fail and users are ready to cope with
3763  		 * that. 1/4 retries is rather arbitrary but we would
3764  		 * need much more detailed feedback from compaction to
3765  		 * make a better decision.
3766  		 */
3767  		if (order > PAGE_ALLOC_COSTLY_ORDER)
3768  			max_retries /= 4;
3769  
3770  		if (++(*compaction_retries) <= max_retries) {
3771  			ret = true;
3772  			goto out;
3773  		}
3774  	}
3775  
3776  	/*
3777  	 * Compaction failed. Retry with increasing priority.
3778  	 */
3779  	min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ?
3780  			MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY;
3781  
3782  	if (*compact_priority > min_priority) {
3783  		(*compact_priority)--;
3784  		*compaction_retries = 0;
3785  		ret = true;
3786  	}
3787  out:
3788  	trace_compact_retry(order, priority, compact_result, retries, max_retries, ret);
3789  	return ret;
3790  }
3791  #else
3792  static inline struct page *
__alloc_pages_direct_compact(gfp_t gfp_mask,unsigned int order,unsigned int alloc_flags,const struct alloc_context * ac,enum compact_priority prio,enum compact_result * compact_result)3793  __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
3794  		unsigned int alloc_flags, const struct alloc_context *ac,
3795  		enum compact_priority prio, enum compact_result *compact_result)
3796  {
3797  	*compact_result = COMPACT_SKIPPED;
3798  	return NULL;
3799  }
3800  
3801  static inline bool
should_compact_retry(struct alloc_context * ac,unsigned int order,int alloc_flags,enum compact_result compact_result,enum compact_priority * compact_priority,int * compaction_retries)3802  should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
3803  		     enum compact_result compact_result,
3804  		     enum compact_priority *compact_priority,
3805  		     int *compaction_retries)
3806  {
3807  	struct zone *zone;
3808  	struct zoneref *z;
3809  
3810  	if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
3811  		return false;
3812  
3813  	/*
3814  	 * There are setups with compaction disabled which would prefer to loop
3815  	 * inside the allocator rather than hit the oom killer prematurely.
3816  	 * Let's give them a good hope and keep retrying while the order-0
3817  	 * watermarks are OK.
3818  	 */
3819  	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
3820  				ac->highest_zoneidx, ac->nodemask) {
3821  		if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
3822  					ac->highest_zoneidx, alloc_flags))
3823  			return true;
3824  	}
3825  	return false;
3826  }
3827  #endif /* CONFIG_COMPACTION */
3828  
3829  #ifdef CONFIG_LOCKDEP
3830  static struct lockdep_map __fs_reclaim_map =
3831  	STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
3832  
__need_reclaim(gfp_t gfp_mask)3833  static bool __need_reclaim(gfp_t gfp_mask)
3834  {
3835  	/* no reclaim without waiting on it */
3836  	if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
3837  		return false;
3838  
3839  	/* this guy won't enter reclaim */
3840  	if (current->flags & PF_MEMALLOC)
3841  		return false;
3842  
3843  	if (gfp_mask & __GFP_NOLOCKDEP)
3844  		return false;
3845  
3846  	return true;
3847  }
3848  
__fs_reclaim_acquire(unsigned long ip)3849  void __fs_reclaim_acquire(unsigned long ip)
3850  {
3851  	lock_acquire_exclusive(&__fs_reclaim_map, 0, 0, NULL, ip);
3852  }
3853  
__fs_reclaim_release(unsigned long ip)3854  void __fs_reclaim_release(unsigned long ip)
3855  {
3856  	lock_release(&__fs_reclaim_map, ip);
3857  }
3858  
fs_reclaim_acquire(gfp_t gfp_mask)3859  void fs_reclaim_acquire(gfp_t gfp_mask)
3860  {
3861  	gfp_mask = current_gfp_context(gfp_mask);
3862  
3863  	if (__need_reclaim(gfp_mask)) {
3864  		if (gfp_mask & __GFP_FS)
3865  			__fs_reclaim_acquire(_RET_IP_);
3866  
3867  #ifdef CONFIG_MMU_NOTIFIER
3868  		lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
3869  		lock_map_release(&__mmu_notifier_invalidate_range_start_map);
3870  #endif
3871  
3872  	}
3873  }
3874  EXPORT_SYMBOL_GPL(fs_reclaim_acquire);
3875  
fs_reclaim_release(gfp_t gfp_mask)3876  void fs_reclaim_release(gfp_t gfp_mask)
3877  {
3878  	gfp_mask = current_gfp_context(gfp_mask);
3879  
3880  	if (__need_reclaim(gfp_mask)) {
3881  		if (gfp_mask & __GFP_FS)
3882  			__fs_reclaim_release(_RET_IP_);
3883  	}
3884  }
3885  EXPORT_SYMBOL_GPL(fs_reclaim_release);
3886  #endif
3887  
3888  /*
3889   * Zonelists may change due to hotplug during allocation. Detect when zonelists
3890   * have been rebuilt so allocation retries. Reader side does not lock and
3891   * retries the allocation if zonelist changes. Writer side is protected by the
3892   * embedded spin_lock.
3893   */
3894  static DEFINE_SEQLOCK(zonelist_update_seq);
3895  
zonelist_iter_begin(void)3896  static unsigned int zonelist_iter_begin(void)
3897  {
3898  	if (IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
3899  		return read_seqbegin(&zonelist_update_seq);
3900  
3901  	return 0;
3902  }
3903  
check_retry_zonelist(unsigned int seq)3904  static unsigned int check_retry_zonelist(unsigned int seq)
3905  {
3906  	if (IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
3907  		return read_seqretry(&zonelist_update_seq, seq);
3908  
3909  	return seq;
3910  }
3911  
3912  /* Perform direct synchronous page reclaim */
3913  static unsigned long
__perform_reclaim(gfp_t gfp_mask,unsigned int order,const struct alloc_context * ac)3914  __perform_reclaim(gfp_t gfp_mask, unsigned int order,
3915  					const struct alloc_context *ac)
3916  {
3917  	unsigned int noreclaim_flag;
3918  	unsigned long progress;
3919  
3920  	cond_resched();
3921  
3922  	/* We now go into synchronous reclaim */
3923  	cpuset_memory_pressure_bump();
3924  	fs_reclaim_acquire(gfp_mask);
3925  	noreclaim_flag = memalloc_noreclaim_save();
3926  
3927  	progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
3928  								ac->nodemask);
3929  
3930  	memalloc_noreclaim_restore(noreclaim_flag);
3931  	fs_reclaim_release(gfp_mask);
3932  
3933  	cond_resched();
3934  
3935  	return progress;
3936  }
3937  
3938  /* The really slow allocator path where we enter direct reclaim */
3939  static inline struct page *
__alloc_pages_direct_reclaim(gfp_t gfp_mask,unsigned int order,unsigned int alloc_flags,const struct alloc_context * ac,unsigned long * did_some_progress)3940  __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
3941  		unsigned int alloc_flags, const struct alloc_context *ac,
3942  		unsigned long *did_some_progress)
3943  {
3944  	struct page *page = NULL;
3945  	unsigned long pflags;
3946  	bool drained = false;
3947  
3948  	psi_memstall_enter(&pflags);
3949  	*did_some_progress = __perform_reclaim(gfp_mask, order, ac);
3950  	if (unlikely(!(*did_some_progress)))
3951  		goto out;
3952  
3953  retry:
3954  	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
3955  
3956  	/*
3957  	 * If an allocation failed after direct reclaim, it could be because
3958  	 * pages are pinned on the per-cpu lists or in high alloc reserves.
3959  	 * Shrink them and try again
3960  	 */
3961  	if (!page && !drained) {
3962  		unreserve_highatomic_pageblock(ac, false);
3963  		drain_all_pages(NULL);
3964  		drained = true;
3965  		goto retry;
3966  	}
3967  out:
3968  	psi_memstall_leave(&pflags);
3969  
3970  	return page;
3971  }
3972  
wake_all_kswapds(unsigned int order,gfp_t gfp_mask,const struct alloc_context * ac)3973  static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
3974  			     const struct alloc_context *ac)
3975  {
3976  	struct zoneref *z;
3977  	struct zone *zone;
3978  	pg_data_t *last_pgdat = NULL;
3979  	enum zone_type highest_zoneidx = ac->highest_zoneidx;
3980  
3981  	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
3982  					ac->nodemask) {
3983  		if (!managed_zone(zone))
3984  			continue;
3985  		if (last_pgdat != zone->zone_pgdat) {
3986  			wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
3987  			last_pgdat = zone->zone_pgdat;
3988  		}
3989  	}
3990  }
3991  
3992  static inline unsigned int
gfp_to_alloc_flags(gfp_t gfp_mask,unsigned int order)3993  gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
3994  {
3995  	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
3996  
3997  	/*
3998  	 * __GFP_HIGH is assumed to be the same as ALLOC_MIN_RESERVE
3999  	 * and __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
4000  	 * to save two branches.
4001  	 */
4002  	BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_MIN_RESERVE);
4003  	BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);
4004  
4005  	/*
4006  	 * The caller may dip into page reserves a bit more if the caller
4007  	 * cannot run direct reclaim, or if the caller has realtime scheduling
4008  	 * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
4009  	 * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH).
4010  	 */
4011  	alloc_flags |= (__force int)
4012  		(gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM));
4013  
4014  	if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
4015  		/*
4016  		 * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
4017  		 * if it can't schedule.
4018  		 */
4019  		if (!(gfp_mask & __GFP_NOMEMALLOC)) {
4020  			alloc_flags |= ALLOC_NON_BLOCK;
4021  
4022  			if (order > 0)
4023  				alloc_flags |= ALLOC_HIGHATOMIC;
4024  		}
4025  
4026  		/*
4027  		 * Ignore cpuset mems for non-blocking __GFP_HIGH (probably
4028  		 * GFP_ATOMIC) rather than fail, see the comment for
4029  		 * cpuset_node_allowed().
4030  		 */
4031  		if (alloc_flags & ALLOC_MIN_RESERVE)
4032  			alloc_flags &= ~ALLOC_CPUSET;
4033  	} else if (unlikely(rt_or_dl_task(current)) && in_task())
4034  		alloc_flags |= ALLOC_MIN_RESERVE;
4035  
4036  	alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
4037  
4038  	return alloc_flags;
4039  }
4040  
oom_reserves_allowed(struct task_struct * tsk)4041  static bool oom_reserves_allowed(struct task_struct *tsk)
4042  {
4043  	if (!tsk_is_oom_victim(tsk))
4044  		return false;
4045  
4046  	/*
4047  	 * !MMU doesn't have oom reaper so give access to memory reserves
4048  	 * only to the thread with TIF_MEMDIE set
4049  	 */
4050  	if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
4051  		return false;
4052  
4053  	return true;
4054  }
4055  
4056  /*
4057   * Distinguish requests which really need access to full memory
4058   * reserves from oom victims which can live with a portion of it
4059   */
__gfp_pfmemalloc_flags(gfp_t gfp_mask)4060  static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
4061  {
4062  	if (unlikely(gfp_mask & __GFP_NOMEMALLOC))
4063  		return 0;
4064  	if (gfp_mask & __GFP_MEMALLOC)
4065  		return ALLOC_NO_WATERMARKS;
4066  	if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
4067  		return ALLOC_NO_WATERMARKS;
4068  	if (!in_interrupt()) {
4069  		if (current->flags & PF_MEMALLOC)
4070  			return ALLOC_NO_WATERMARKS;
4071  		else if (oom_reserves_allowed(current))
4072  			return ALLOC_OOM;
4073  	}
4074  
4075  	return 0;
4076  }
4077  
gfp_pfmemalloc_allowed(gfp_t gfp_mask)4078  bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
4079  {
4080  	return !!__gfp_pfmemalloc_flags(gfp_mask);
4081  }
4082  
4083  /*
4084   * Checks whether it makes sense to retry the reclaim to make a forward progress
4085   * for the given allocation request.
4086   *
4087   * We give up when we either have tried MAX_RECLAIM_RETRIES in a row
4088   * without success, or when we couldn't even meet the watermark if we
4089   * reclaimed all remaining pages on the LRU lists.
4090   *
4091   * Returns true if a retry is viable or false to enter the oom path.
4092   */
4093  static inline bool
should_reclaim_retry(gfp_t gfp_mask,unsigned order,struct alloc_context * ac,int alloc_flags,bool did_some_progress,int * no_progress_loops)4094  should_reclaim_retry(gfp_t gfp_mask, unsigned order,
4095  		     struct alloc_context *ac, int alloc_flags,
4096  		     bool did_some_progress, int *no_progress_loops)
4097  {
4098  	struct zone *zone;
4099  	struct zoneref *z;
4100  	bool ret = false;
4101  
4102  	/*
4103  	 * Costly allocations might have made a progress but this doesn't mean
4104  	 * their order will become available due to high fragmentation so
4105  	 * always increment the no progress counter for them
4106  	 */
4107  	if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
4108  		*no_progress_loops = 0;
4109  	else
4110  		(*no_progress_loops)++;
4111  
4112  	if (*no_progress_loops > MAX_RECLAIM_RETRIES)
4113  		goto out;
4114  
4115  
4116  	/*
4117  	 * Keep reclaiming pages while there is a chance this will lead
4118  	 * somewhere.  If none of the target zones can satisfy our allocation
4119  	 * request even if all reclaimable pages are considered then we are
4120  	 * screwed and have to go OOM.
4121  	 */
4122  	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
4123  				ac->highest_zoneidx, ac->nodemask) {
4124  		unsigned long available;
4125  		unsigned long reclaimable;
4126  		unsigned long min_wmark = min_wmark_pages(zone);
4127  		bool wmark;
4128  
4129  		if (cpusets_enabled() &&
4130  			(alloc_flags & ALLOC_CPUSET) &&
4131  			!__cpuset_zone_allowed(zone, gfp_mask))
4132  				continue;
4133  
4134  		available = reclaimable = zone_reclaimable_pages(zone);
4135  		available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
4136  
4137  		/*
4138  		 * Would the allocation succeed if we reclaimed all
4139  		 * reclaimable pages?
4140  		 */
4141  		wmark = __zone_watermark_ok(zone, order, min_wmark,
4142  				ac->highest_zoneidx, alloc_flags, available);
4143  		trace_reclaim_retry_zone(z, order, reclaimable,
4144  				available, min_wmark, *no_progress_loops, wmark);
4145  		if (wmark) {
4146  			ret = true;
4147  			break;
4148  		}
4149  	}
4150  
4151  	/*
4152  	 * Memory allocation/reclaim might be called from a WQ context and the
4153  	 * current implementation of the WQ concurrency control doesn't
4154  	 * recognize that a particular WQ is congested if the worker thread is
4155  	 * looping without ever sleeping. Therefore we have to do a short sleep
4156  	 * here rather than calling cond_resched().
4157  	 */
4158  	if (current->flags & PF_WQ_WORKER)
4159  		schedule_timeout_uninterruptible(1);
4160  	else
4161  		cond_resched();
4162  out:
4163  	/* Before OOM, exhaust highatomic_reserve */
4164  	if (!ret)
4165  		return unreserve_highatomic_pageblock(ac, true);
4166  
4167  	return ret;
4168  }
4169  
4170  static inline bool
check_retry_cpuset(int cpuset_mems_cookie,struct alloc_context * ac)4171  check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
4172  {
4173  	/*
4174  	 * It's possible that cpuset's mems_allowed and the nodemask from
4175  	 * mempolicy don't intersect. This should be normally dealt with by
4176  	 * policy_nodemask(), but it's possible to race with cpuset update in
4177  	 * such a way the check therein was true, and then it became false
4178  	 * before we got our cpuset_mems_cookie here.
4179  	 * This assumes that for all allocations, ac->nodemask can come only
4180  	 * from MPOL_BIND mempolicy (whose documented semantics is to be ignored
4181  	 * when it does not intersect with the cpuset restrictions) or the
4182  	 * caller can deal with a violated nodemask.
4183  	 */
4184  	if (cpusets_enabled() && ac->nodemask &&
4185  			!cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
4186  		ac->nodemask = NULL;
4187  		return true;
4188  	}
4189  
4190  	/*
4191  	 * When updating a task's mems_allowed or mempolicy nodemask, it is
4192  	 * possible to race with parallel threads in such a way that our
4193  	 * allocation can fail while the mask is being updated. If we are about
4194  	 * to fail, check if the cpuset changed during allocation and if so,
4195  	 * retry.
4196  	 */
4197  	if (read_mems_allowed_retry(cpuset_mems_cookie))
4198  		return true;
4199  
4200  	return false;
4201  }
4202  
4203  static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask,unsigned int order,struct alloc_context * ac)4204  __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
4205  						struct alloc_context *ac)
4206  {
4207  	bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
4208  	bool can_compact = gfp_compaction_allowed(gfp_mask);
4209  	bool nofail = gfp_mask & __GFP_NOFAIL;
4210  	const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER;
4211  	struct page *page = NULL;
4212  	unsigned int alloc_flags;
4213  	unsigned long did_some_progress;
4214  	enum compact_priority compact_priority;
4215  	enum compact_result compact_result;
4216  	int compaction_retries;
4217  	int no_progress_loops;
4218  	unsigned int cpuset_mems_cookie;
4219  	unsigned int zonelist_iter_cookie;
4220  	int reserve_flags;
4221  
4222  	if (unlikely(nofail)) {
4223  		/*
4224  		 * We most definitely don't want callers attempting to
4225  		 * allocate greater than order-1 page units with __GFP_NOFAIL.
4226  		 */
4227  		WARN_ON_ONCE(order > 1);
4228  		/*
4229  		 * Also we don't support __GFP_NOFAIL without __GFP_DIRECT_RECLAIM,
4230  		 * otherwise, we may result in lockup.
4231  		 */
4232  		WARN_ON_ONCE(!can_direct_reclaim);
4233  		/*
4234  		 * PF_MEMALLOC request from this context is rather bizarre
4235  		 * because we cannot reclaim anything and only can loop waiting
4236  		 * for somebody to do a work for us.
4237  		 */
4238  		WARN_ON_ONCE(current->flags & PF_MEMALLOC);
4239  	}
4240  
4241  restart:
4242  	compaction_retries = 0;
4243  	no_progress_loops = 0;
4244  	compact_priority = DEF_COMPACT_PRIORITY;
4245  	cpuset_mems_cookie = read_mems_allowed_begin();
4246  	zonelist_iter_cookie = zonelist_iter_begin();
4247  
4248  	/*
4249  	 * The fast path uses conservative alloc_flags to succeed only until
4250  	 * kswapd needs to be woken up, and to avoid the cost of setting up
4251  	 * alloc_flags precisely. So we do that now.
4252  	 */
4253  	alloc_flags = gfp_to_alloc_flags(gfp_mask, order);
4254  
4255  	/*
4256  	 * We need to recalculate the starting point for the zonelist iterator
4257  	 * because we might have used different nodemask in the fast path, or
4258  	 * there was a cpuset modification and we are retrying - otherwise we
4259  	 * could end up iterating over non-eligible zones endlessly.
4260  	 */
4261  	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
4262  					ac->highest_zoneidx, ac->nodemask);
4263  	if (!zonelist_zone(ac->preferred_zoneref))
4264  		goto nopage;
4265  
4266  	/*
4267  	 * Check for insane configurations where the cpuset doesn't contain
4268  	 * any suitable zone to satisfy the request - e.g. non-movable
4269  	 * GFP_HIGHUSER allocations from MOVABLE nodes only.
4270  	 */
4271  	if (cpusets_insane_config() && (gfp_mask & __GFP_HARDWALL)) {
4272  		struct zoneref *z = first_zones_zonelist(ac->zonelist,
4273  					ac->highest_zoneidx,
4274  					&cpuset_current_mems_allowed);
4275  		if (!zonelist_zone(z))
4276  			goto nopage;
4277  	}
4278  
4279  	if (alloc_flags & ALLOC_KSWAPD)
4280  		wake_all_kswapds(order, gfp_mask, ac);
4281  
4282  	/*
4283  	 * The adjusted alloc_flags might result in immediate success, so try
4284  	 * that first
4285  	 */
4286  	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4287  	if (page)
4288  		goto got_pg;
4289  
4290  	/*
4291  	 * For costly allocations, try direct compaction first, as it's likely
4292  	 * that we have enough base pages and don't need to reclaim. For non-
4293  	 * movable high-order allocations, do that as well, as compaction will
4294  	 * try prevent permanent fragmentation by migrating from blocks of the
4295  	 * same migratetype.
4296  	 * Don't try this for allocations that are allowed to ignore
4297  	 * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen.
4298  	 */
4299  	if (can_direct_reclaim && can_compact &&
4300  			(costly_order ||
4301  			   (order > 0 && ac->migratetype != MIGRATE_MOVABLE))
4302  			&& !gfp_pfmemalloc_allowed(gfp_mask)) {
4303  		page = __alloc_pages_direct_compact(gfp_mask, order,
4304  						alloc_flags, ac,
4305  						INIT_COMPACT_PRIORITY,
4306  						&compact_result);
4307  		if (page)
4308  			goto got_pg;
4309  
4310  		/*
4311  		 * Checks for costly allocations with __GFP_NORETRY, which
4312  		 * includes some THP page fault allocations
4313  		 */
4314  		if (costly_order && (gfp_mask & __GFP_NORETRY)) {
4315  			/*
4316  			 * If allocating entire pageblock(s) and compaction
4317  			 * failed because all zones are below low watermarks
4318  			 * or is prohibited because it recently failed at this
4319  			 * order, fail immediately unless the allocator has
4320  			 * requested compaction and reclaim retry.
4321  			 *
4322  			 * Reclaim is
4323  			 *  - potentially very expensive because zones are far
4324  			 *    below their low watermarks or this is part of very
4325  			 *    bursty high order allocations,
4326  			 *  - not guaranteed to help because isolate_freepages()
4327  			 *    may not iterate over freed pages as part of its
4328  			 *    linear scan, and
4329  			 *  - unlikely to make entire pageblocks free on its
4330  			 *    own.
4331  			 */
4332  			if (compact_result == COMPACT_SKIPPED ||
4333  			    compact_result == COMPACT_DEFERRED)
4334  				goto nopage;
4335  
4336  			/*
4337  			 * Looks like reclaim/compaction is worth trying, but
4338  			 * sync compaction could be very expensive, so keep
4339  			 * using async compaction.
4340  			 */
4341  			compact_priority = INIT_COMPACT_PRIORITY;
4342  		}
4343  	}
4344  
4345  retry:
4346  	/* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
4347  	if (alloc_flags & ALLOC_KSWAPD)
4348  		wake_all_kswapds(order, gfp_mask, ac);
4349  
4350  	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
4351  	if (reserve_flags)
4352  		alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags) |
4353  					  (alloc_flags & ALLOC_KSWAPD);
4354  
4355  	/*
4356  	 * Reset the nodemask and zonelist iterators if memory policies can be
4357  	 * ignored. These allocations are high priority and system rather than
4358  	 * user oriented.
4359  	 */
4360  	if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
4361  		ac->nodemask = NULL;
4362  		ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
4363  					ac->highest_zoneidx, ac->nodemask);
4364  	}
4365  
4366  	/* Attempt with potentially adjusted zonelist and alloc_flags */
4367  	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4368  	if (page)
4369  		goto got_pg;
4370  
4371  	/* Caller is not willing to reclaim, we can't balance anything */
4372  	if (!can_direct_reclaim)
4373  		goto nopage;
4374  
4375  	/* Avoid recursion of direct reclaim */
4376  	if (current->flags & PF_MEMALLOC)
4377  		goto nopage;
4378  
4379  	/* Try direct reclaim and then allocating */
4380  	page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
4381  							&did_some_progress);
4382  	if (page)
4383  		goto got_pg;
4384  
4385  	/* Try direct compaction and then allocating */
4386  	page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
4387  					compact_priority, &compact_result);
4388  	if (page)
4389  		goto got_pg;
4390  
4391  	/* Do not loop if specifically requested */
4392  	if (gfp_mask & __GFP_NORETRY)
4393  		goto nopage;
4394  
4395  	/*
4396  	 * Do not retry costly high order allocations unless they are
4397  	 * __GFP_RETRY_MAYFAIL and we can compact
4398  	 */
4399  	if (costly_order && (!can_compact ||
4400  			     !(gfp_mask & __GFP_RETRY_MAYFAIL)))
4401  		goto nopage;
4402  
4403  	if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
4404  				 did_some_progress > 0, &no_progress_loops))
4405  		goto retry;
4406  
4407  	/*
4408  	 * It doesn't make any sense to retry for the compaction if the order-0
4409  	 * reclaim is not able to make any progress because the current
4410  	 * implementation of the compaction depends on the sufficient amount
4411  	 * of free memory (see __compaction_suitable)
4412  	 */
4413  	if (did_some_progress > 0 && can_compact &&
4414  			should_compact_retry(ac, order, alloc_flags,
4415  				compact_result, &compact_priority,
4416  				&compaction_retries))
4417  		goto retry;
4418  
4419  
4420  	/*
4421  	 * Deal with possible cpuset update races or zonelist updates to avoid
4422  	 * a unnecessary OOM kill.
4423  	 */
4424  	if (check_retry_cpuset(cpuset_mems_cookie, ac) ||
4425  	    check_retry_zonelist(zonelist_iter_cookie))
4426  		goto restart;
4427  
4428  	/* Reclaim has failed us, start killing things */
4429  	page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
4430  	if (page)
4431  		goto got_pg;
4432  
4433  	/* Avoid allocations with no watermarks from looping endlessly */
4434  	if (tsk_is_oom_victim(current) &&
4435  	    (alloc_flags & ALLOC_OOM ||
4436  	     (gfp_mask & __GFP_NOMEMALLOC)))
4437  		goto nopage;
4438  
4439  	/* Retry as long as the OOM killer is making progress */
4440  	if (did_some_progress) {
4441  		no_progress_loops = 0;
4442  		goto retry;
4443  	}
4444  
4445  nopage:
4446  	/*
4447  	 * Deal with possible cpuset update races or zonelist updates to avoid
4448  	 * a unnecessary OOM kill.
4449  	 */
4450  	if (check_retry_cpuset(cpuset_mems_cookie, ac) ||
4451  	    check_retry_zonelist(zonelist_iter_cookie))
4452  		goto restart;
4453  
4454  	/*
4455  	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
4456  	 * we always retry
4457  	 */
4458  	if (unlikely(nofail)) {
4459  		/*
4460  		 * Lacking direct_reclaim we can't do anything to reclaim memory,
4461  		 * we disregard these unreasonable nofail requests and still
4462  		 * return NULL
4463  		 */
4464  		if (!can_direct_reclaim)
4465  			goto fail;
4466  
4467  		/*
4468  		 * Help non-failing allocations by giving some access to memory
4469  		 * reserves normally used for high priority non-blocking
4470  		 * allocations but do not use ALLOC_NO_WATERMARKS because this
4471  		 * could deplete whole memory reserves which would just make
4472  		 * the situation worse.
4473  		 */
4474  		page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERVE, ac);
4475  		if (page)
4476  			goto got_pg;
4477  
4478  		cond_resched();
4479  		goto retry;
4480  	}
4481  fail:
4482  	warn_alloc(gfp_mask, ac->nodemask,
4483  			"page allocation failure: order:%u", order);
4484  got_pg:
4485  	return page;
4486  }
4487  
prepare_alloc_pages(gfp_t gfp_mask,unsigned int order,int preferred_nid,nodemask_t * nodemask,struct alloc_context * ac,gfp_t * alloc_gfp,unsigned int * alloc_flags)4488  static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
4489  		int preferred_nid, nodemask_t *nodemask,
4490  		struct alloc_context *ac, gfp_t *alloc_gfp,
4491  		unsigned int *alloc_flags)
4492  {
4493  	ac->highest_zoneidx = gfp_zone(gfp_mask);
4494  	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
4495  	ac->nodemask = nodemask;
4496  	ac->migratetype = gfp_migratetype(gfp_mask);
4497  
4498  	if (cpusets_enabled()) {
4499  		*alloc_gfp |= __GFP_HARDWALL;
4500  		/*
4501  		 * When we are in the interrupt context, it is irrelevant
4502  		 * to the current task context. It means that any node ok.
4503  		 */
4504  		if (in_task() && !ac->nodemask)
4505  			ac->nodemask = &cpuset_current_mems_allowed;
4506  		else
4507  			*alloc_flags |= ALLOC_CPUSET;
4508  	}
4509  
4510  	might_alloc(gfp_mask);
4511  
4512  	if (should_fail_alloc_page(gfp_mask, order))
4513  		return false;
4514  
4515  	*alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags);
4516  
4517  	/* Dirty zone balancing only done in the fast path */
4518  	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
4519  
4520  	/*
4521  	 * The preferred zone is used for statistics but crucially it is
4522  	 * also used as the starting point for the zonelist iterator. It
4523  	 * may get reset for allocations that ignore memory policies.
4524  	 */
4525  	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
4526  					ac->highest_zoneidx, ac->nodemask);
4527  
4528  	return true;
4529  }
4530  
4531  /*
4532   * __alloc_pages_bulk - Allocate a number of order-0 pages to a list or array
4533   * @gfp: GFP flags for the allocation
4534   * @preferred_nid: The preferred NUMA node ID to allocate from
4535   * @nodemask: Set of nodes to allocate from, may be NULL
4536   * @nr_pages: The number of pages desired on the list or array
4537   * @page_list: Optional list to store the allocated pages
4538   * @page_array: Optional array to store the pages
4539   *
4540   * This is a batched version of the page allocator that attempts to
4541   * allocate nr_pages quickly. Pages are added to page_list if page_list
4542   * is not NULL, otherwise it is assumed that the page_array is valid.
4543   *
4544   * For lists, nr_pages is the number of pages that should be allocated.
4545   *
4546   * For arrays, only NULL elements are populated with pages and nr_pages
4547   * is the maximum number of pages that will be stored in the array.
4548   *
4549   * Returns the number of pages on the list or array.
4550   */
alloc_pages_bulk_noprof(gfp_t gfp,int preferred_nid,nodemask_t * nodemask,int nr_pages,struct list_head * page_list,struct page ** page_array)4551  unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
4552  			nodemask_t *nodemask, int nr_pages,
4553  			struct list_head *page_list,
4554  			struct page **page_array)
4555  {
4556  	struct page *page;
4557  	unsigned long __maybe_unused UP_flags;
4558  	struct zone *zone;
4559  	struct zoneref *z;
4560  	struct per_cpu_pages *pcp;
4561  	struct list_head *pcp_list;
4562  	struct alloc_context ac;
4563  	gfp_t alloc_gfp;
4564  	unsigned int alloc_flags = ALLOC_WMARK_LOW;
4565  	int nr_populated = 0, nr_account = 0;
4566  
4567  	/*
4568  	 * Skip populated array elements to determine if any pages need
4569  	 * to be allocated before disabling IRQs.
4570  	 */
4571  	while (page_array && nr_populated < nr_pages && page_array[nr_populated])
4572  		nr_populated++;
4573  
4574  	/* No pages requested? */
4575  	if (unlikely(nr_pages <= 0))
4576  		goto out;
4577  
4578  	/* Already populated array? */
4579  	if (unlikely(page_array && nr_pages - nr_populated == 0))
4580  		goto out;
4581  
4582  	/* Bulk allocator does not support memcg accounting. */
4583  	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT))
4584  		goto failed;
4585  
4586  	/* Use the single page allocator for one page. */
4587  	if (nr_pages - nr_populated == 1)
4588  		goto failed;
4589  
4590  #ifdef CONFIG_PAGE_OWNER
4591  	/*
4592  	 * PAGE_OWNER may recurse into the allocator to allocate space to
4593  	 * save the stack with pagesets.lock held. Releasing/reacquiring
4594  	 * removes much of the performance benefit of bulk allocation so
4595  	 * force the caller to allocate one page at a time as it'll have
4596  	 * similar performance to added complexity to the bulk allocator.
4597  	 */
4598  	if (static_branch_unlikely(&page_owner_inited))
4599  		goto failed;
4600  #endif
4601  
4602  	/* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */
4603  	gfp &= gfp_allowed_mask;
4604  	alloc_gfp = gfp;
4605  	if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
4606  		goto out;
4607  	gfp = alloc_gfp;
4608  
4609  	/* Find an allowed local zone that meets the low watermark. */
4610  	z = ac.preferred_zoneref;
4611  	for_next_zone_zonelist_nodemask(zone, z, ac.highest_zoneidx, ac.nodemask) {
4612  		unsigned long mark;
4613  
4614  		if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
4615  		    !__cpuset_zone_allowed(zone, gfp)) {
4616  			continue;
4617  		}
4618  
4619  		if (nr_online_nodes > 1 && zone != zonelist_zone(ac.preferred_zoneref) &&
4620  		    zone_to_nid(zone) != zonelist_node_idx(ac.preferred_zoneref)) {
4621  			goto failed;
4622  		}
4623  
4624  		cond_accept_memory(zone, 0);
4625  retry_this_zone:
4626  		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
4627  		if (zone_watermark_fast(zone, 0,  mark,
4628  				zonelist_zone_idx(ac.preferred_zoneref),
4629  				alloc_flags, gfp)) {
4630  			break;
4631  		}
4632  
4633  		if (cond_accept_memory(zone, 0))
4634  			goto retry_this_zone;
4635  
4636  		/* Try again if zone has deferred pages */
4637  		if (deferred_pages_enabled()) {
4638  			if (_deferred_grow_zone(zone, 0))
4639  				goto retry_this_zone;
4640  		}
4641  	}
4642  
4643  	/*
4644  	 * If there are no allowed local zones that meets the watermarks then
4645  	 * try to allocate a single page and reclaim if necessary.
4646  	 */
4647  	if (unlikely(!zone))
4648  		goto failed;
4649  
4650  	/* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */
4651  	pcp_trylock_prepare(UP_flags);
4652  	pcp = pcp_spin_trylock(zone->per_cpu_pageset);
4653  	if (!pcp)
4654  		goto failed_irq;
4655  
4656  	/* Attempt the batch allocation */
4657  	pcp_list = &pcp->lists[order_to_pindex(ac.migratetype, 0)];
4658  	while (nr_populated < nr_pages) {
4659  
4660  		/* Skip existing pages */
4661  		if (page_array && page_array[nr_populated]) {
4662  			nr_populated++;
4663  			continue;
4664  		}
4665  
4666  		page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
4667  								pcp, pcp_list);
4668  		if (unlikely(!page)) {
4669  			/* Try and allocate at least one page */
4670  			if (!nr_account) {
4671  				pcp_spin_unlock(pcp);
4672  				goto failed_irq;
4673  			}
4674  			break;
4675  		}
4676  		nr_account++;
4677  
4678  		prep_new_page(page, 0, gfp, 0);
4679  		if (page_list)
4680  			list_add(&page->lru, page_list);
4681  		else
4682  			page_array[nr_populated] = page;
4683  		nr_populated++;
4684  	}
4685  
4686  	pcp_spin_unlock(pcp);
4687  	pcp_trylock_finish(UP_flags);
4688  
4689  	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
4690  	zone_statistics(zonelist_zone(ac.preferred_zoneref), zone, nr_account);
4691  
4692  out:
4693  	return nr_populated;
4694  
4695  failed_irq:
4696  	pcp_trylock_finish(UP_flags);
4697  
4698  failed:
4699  	page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask);
4700  	if (page) {
4701  		if (page_list)
4702  			list_add(&page->lru, page_list);
4703  		else
4704  			page_array[nr_populated] = page;
4705  		nr_populated++;
4706  	}
4707  
4708  	goto out;
4709  }
4710  EXPORT_SYMBOL_GPL(alloc_pages_bulk_noprof);
4711  
4712  /*
4713   * This is the 'heart' of the zoned buddy allocator.
4714   */
__alloc_pages_noprof(gfp_t gfp,unsigned int order,int preferred_nid,nodemask_t * nodemask)4715  struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
4716  				      int preferred_nid, nodemask_t *nodemask)
4717  {
4718  	struct page *page;
4719  	unsigned int alloc_flags = ALLOC_WMARK_LOW;
4720  	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
4721  	struct alloc_context ac = { };
4722  
4723  	/*
4724  	 * There are several places where we assume that the order value is sane
4725  	 * so bail out early if the request is out of bound.
4726  	 */
4727  	if (WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp))
4728  		return NULL;
4729  
4730  	gfp &= gfp_allowed_mask;
4731  	/*
4732  	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
4733  	 * resp. GFP_NOIO which has to be inherited for all allocation requests
4734  	 * from a particular context which has been marked by
4735  	 * memalloc_no{fs,io}_{save,restore}. And PF_MEMALLOC_PIN which ensures
4736  	 * movable zones are not used during allocation.
4737  	 */
4738  	gfp = current_gfp_context(gfp);
4739  	alloc_gfp = gfp;
4740  	if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
4741  			&alloc_gfp, &alloc_flags))
4742  		return NULL;
4743  
4744  	/*
4745  	 * Forbid the first pass from falling back to types that fragment
4746  	 * memory until all local zones are considered.
4747  	 */
4748  	alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
4749  
4750  	/* First allocation attempt */
4751  	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
4752  	if (likely(page))
4753  		goto out;
4754  
4755  	alloc_gfp = gfp;
4756  	ac.spread_dirty_pages = false;
4757  
4758  	/*
4759  	 * Restore the original nodemask if it was potentially replaced with
4760  	 * &cpuset_current_mems_allowed to optimize the fast-path attempt.
4761  	 */
4762  	ac.nodemask = nodemask;
4763  
4764  	page = __alloc_pages_slowpath(alloc_gfp, order, &ac);
4765  
4766  out:
4767  	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
4768  	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
4769  		__free_pages(page, order);
4770  		page = NULL;
4771  	}
4772  
4773  	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
4774  	kmsan_alloc_page(page, order, alloc_gfp);
4775  
4776  	return page;
4777  }
4778  EXPORT_SYMBOL(__alloc_pages_noprof);
4779  
__folio_alloc_noprof(gfp_t gfp,unsigned int order,int preferred_nid,nodemask_t * nodemask)4780  struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
4781  		nodemask_t *nodemask)
4782  {
4783  	struct page *page = __alloc_pages_noprof(gfp | __GFP_COMP, order,
4784  					preferred_nid, nodemask);
4785  	return page_rmappable_folio(page);
4786  }
4787  EXPORT_SYMBOL(__folio_alloc_noprof);
4788  
4789  /*
4790   * Common helper functions. Never use with __GFP_HIGHMEM because the returned
4791   * address cannot represent highmem pages. Use alloc_pages and then kmap if
4792   * you need to access high mem.
4793   */
get_free_pages_noprof(gfp_t gfp_mask,unsigned int order)4794  unsigned long get_free_pages_noprof(gfp_t gfp_mask, unsigned int order)
4795  {
4796  	struct page *page;
4797  
4798  	page = alloc_pages_noprof(gfp_mask & ~__GFP_HIGHMEM, order);
4799  	if (!page)
4800  		return 0;
4801  	return (unsigned long) page_address(page);
4802  }
4803  EXPORT_SYMBOL(get_free_pages_noprof);
4804  
get_zeroed_page_noprof(gfp_t gfp_mask)4805  unsigned long get_zeroed_page_noprof(gfp_t gfp_mask)
4806  {
4807  	return get_free_pages_noprof(gfp_mask | __GFP_ZERO, 0);
4808  }
4809  EXPORT_SYMBOL(get_zeroed_page_noprof);
4810  
4811  /**
4812   * __free_pages - Free pages allocated with alloc_pages().
4813   * @page: The page pointer returned from alloc_pages().
4814   * @order: The order of the allocation.
4815   *
4816   * This function can free multi-page allocations that are not compound
4817   * pages.  It does not check that the @order passed in matches that of
4818   * the allocation, so it is easy to leak memory.  Freeing more memory
4819   * than was allocated will probably emit a warning.
4820   *
4821   * If the last reference to this page is speculative, it will be released
4822   * by put_page() which only frees the first page of a non-compound
4823   * allocation.  To prevent the remaining pages from being leaked, we free
4824   * the subsequent pages here.  If you want to use the page's reference
4825   * count to decide when to free the allocation, you should allocate a
4826   * compound page, and use put_page() instead of __free_pages().
4827   *
4828   * Context: May be called in interrupt context or while holding a normal
4829   * spinlock, but not in NMI context or while holding a raw spinlock.
4830   */
__free_pages(struct page * page,unsigned int order)4831  void __free_pages(struct page *page, unsigned int order)
4832  {
4833  	/* get PageHead before we drop reference */
4834  	int head = PageHead(page);
4835  	struct alloc_tag *tag = pgalloc_tag_get(page);
4836  
4837  	if (put_page_testzero(page))
4838  		free_unref_page(page, order);
4839  	else if (!head) {
4840  		pgalloc_tag_sub_pages(tag, (1 << order) - 1);
4841  		while (order-- > 0)
4842  			free_unref_page(page + (1 << order), order);
4843  	}
4844  }
4845  EXPORT_SYMBOL(__free_pages);
4846  
free_pages(unsigned long addr,unsigned int order)4847  void free_pages(unsigned long addr, unsigned int order)
4848  {
4849  	if (addr != 0) {
4850  		VM_BUG_ON(!virt_addr_valid((void *)addr));
4851  		__free_pages(virt_to_page((void *)addr), order);
4852  	}
4853  }
4854  
4855  EXPORT_SYMBOL(free_pages);
4856  
4857  /*
4858   * Page Fragment:
4859   *  An arbitrary-length arbitrary-offset area of memory which resides
4860   *  within a 0 or higher order page.  Multiple fragments within that page
4861   *  are individually refcounted, in the page's reference counter.
4862   *
4863   * The page_frag functions below provide a simple allocation framework for
4864   * page fragments.  This is used by the network stack and network device
4865   * drivers to provide a backing region of memory for use as either an
4866   * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
4867   */
__page_frag_cache_refill(struct page_frag_cache * nc,gfp_t gfp_mask)4868  static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
4869  					     gfp_t gfp_mask)
4870  {
4871  	struct page *page = NULL;
4872  	gfp_t gfp = gfp_mask;
4873  
4874  #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
4875  	gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) |  __GFP_COMP |
4876  		   __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC;
4877  	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
4878  				PAGE_FRAG_CACHE_MAX_ORDER);
4879  	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
4880  #endif
4881  	if (unlikely(!page))
4882  		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
4883  
4884  	nc->va = page ? page_address(page) : NULL;
4885  
4886  	return page;
4887  }
4888  
page_frag_cache_drain(struct page_frag_cache * nc)4889  void page_frag_cache_drain(struct page_frag_cache *nc)
4890  {
4891  	if (!nc->va)
4892  		return;
4893  
4894  	__page_frag_cache_drain(virt_to_head_page(nc->va), nc->pagecnt_bias);
4895  	nc->va = NULL;
4896  }
4897  EXPORT_SYMBOL(page_frag_cache_drain);
4898  
__page_frag_cache_drain(struct page * page,unsigned int count)4899  void __page_frag_cache_drain(struct page *page, unsigned int count)
4900  {
4901  	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
4902  
4903  	if (page_ref_sub_and_test(page, count))
4904  		free_unref_page(page, compound_order(page));
4905  }
4906  EXPORT_SYMBOL(__page_frag_cache_drain);
4907  
__page_frag_alloc_align(struct page_frag_cache * nc,unsigned int fragsz,gfp_t gfp_mask,unsigned int align_mask)4908  void *__page_frag_alloc_align(struct page_frag_cache *nc,
4909  			      unsigned int fragsz, gfp_t gfp_mask,
4910  			      unsigned int align_mask)
4911  {
4912  	unsigned int size = PAGE_SIZE;
4913  	struct page *page;
4914  	int offset;
4915  
4916  	if (unlikely(!nc->va)) {
4917  refill:
4918  		page = __page_frag_cache_refill(nc, gfp_mask);
4919  		if (!page)
4920  			return NULL;
4921  
4922  #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
4923  		/* if size can vary use size else just use PAGE_SIZE */
4924  		size = nc->size;
4925  #endif
4926  		/* Even if we own the page, we do not use atomic_set().
4927  		 * This would break get_page_unless_zero() users.
4928  		 */
4929  		page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);
4930  
4931  		/* reset page count bias and offset to start of new frag */
4932  		nc->pfmemalloc = page_is_pfmemalloc(page);
4933  		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
4934  		nc->offset = size;
4935  	}
4936  
4937  	offset = nc->offset - fragsz;
4938  	if (unlikely(offset < 0)) {
4939  		page = virt_to_page(nc->va);
4940  
4941  		if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
4942  			goto refill;
4943  
4944  		if (unlikely(nc->pfmemalloc)) {
4945  			free_unref_page(page, compound_order(page));
4946  			goto refill;
4947  		}
4948  
4949  #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
4950  		/* if size can vary use size else just use PAGE_SIZE */
4951  		size = nc->size;
4952  #endif
4953  		/* OK, page count is 0, we can safely set it */
4954  		set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);
4955  
4956  		/* reset page count bias and offset to start of new frag */
4957  		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
4958  		offset = size - fragsz;
4959  		if (unlikely(offset < 0)) {
4960  			/*
4961  			 * The caller is trying to allocate a fragment
4962  			 * with fragsz > PAGE_SIZE but the cache isn't big
4963  			 * enough to satisfy the request, this may
4964  			 * happen in low memory conditions.
4965  			 * We don't release the cache page because
4966  			 * it could make memory pressure worse
4967  			 * so we simply return NULL here.
4968  			 */
4969  			return NULL;
4970  		}
4971  	}
4972  
4973  	nc->pagecnt_bias--;
4974  	offset &= align_mask;
4975  	nc->offset = offset;
4976  
4977  	return nc->va + offset;
4978  }
4979  EXPORT_SYMBOL(__page_frag_alloc_align);
4980  
4981  /*
4982   * Frees a page fragment allocated out of either a compound or order 0 page.
4983   */
page_frag_free(void * addr)4984  void page_frag_free(void *addr)
4985  {
4986  	struct page *page = virt_to_head_page(addr);
4987  
4988  	if (unlikely(put_page_testzero(page)))
4989  		free_unref_page(page, compound_order(page));
4990  }
4991  EXPORT_SYMBOL(page_frag_free);
4992  
make_alloc_exact(unsigned long addr,unsigned int order,size_t size)4993  static void *make_alloc_exact(unsigned long addr, unsigned int order,
4994  		size_t size)
4995  {
4996  	if (addr) {
4997  		unsigned long nr = DIV_ROUND_UP(size, PAGE_SIZE);
4998  		struct page *page = virt_to_page((void *)addr);
4999  		struct page *last = page + nr;
5000  
5001  		split_page_owner(page, order, 0);
5002  		pgalloc_tag_split(page_folio(page), order, 0);
5003  		split_page_memcg(page, order, 0);
5004  		while (page < --last)
5005  			set_page_refcounted(last);
5006  
5007  		last = page + (1UL << order);
5008  		for (page += nr; page < last; page++)
5009  			__free_pages_ok(page, 0, FPI_TO_TAIL);
5010  	}
5011  	return (void *)addr;
5012  }
5013  
5014  /**
5015   * alloc_pages_exact - allocate an exact number physically-contiguous pages.
5016   * @size: the number of bytes to allocate
5017   * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
5018   *
5019   * This function is similar to alloc_pages(), except that it allocates the
5020   * minimum number of pages to satisfy the request.  alloc_pages() can only
5021   * allocate memory in power-of-two pages.
5022   *
5023   * This function is also limited by MAX_PAGE_ORDER.
5024   *
5025   * Memory allocated by this function must be released by free_pages_exact().
5026   *
5027   * Return: pointer to the allocated area or %NULL in case of error.
5028   */
alloc_pages_exact_noprof(size_t size,gfp_t gfp_mask)5029  void *alloc_pages_exact_noprof(size_t size, gfp_t gfp_mask)
5030  {
5031  	unsigned int order = get_order(size);
5032  	unsigned long addr;
5033  
5034  	if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
5035  		gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
5036  
5037  	addr = get_free_pages_noprof(gfp_mask, order);
5038  	return make_alloc_exact(addr, order, size);
5039  }
5040  EXPORT_SYMBOL(alloc_pages_exact_noprof);
5041  
5042  /**
5043   * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
5044   *			   pages on a node.
5045   * @nid: the preferred node ID where memory should be allocated
5046   * @size: the number of bytes to allocate
5047   * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
5048   *
5049   * Like alloc_pages_exact(), but try to allocate on node nid first before falling
5050   * back.
5051   *
5052   * Return: pointer to the allocated area or %NULL in case of error.
5053   */
alloc_pages_exact_nid_noprof(int nid,size_t size,gfp_t gfp_mask)5054  void * __meminit alloc_pages_exact_nid_noprof(int nid, size_t size, gfp_t gfp_mask)
5055  {
5056  	unsigned int order = get_order(size);
5057  	struct page *p;
5058  
5059  	if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
5060  		gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
5061  
5062  	p = alloc_pages_node_noprof(nid, gfp_mask, order);
5063  	if (!p)
5064  		return NULL;
5065  	return make_alloc_exact((unsigned long)page_address(p), order, size);
5066  }
5067  
5068  /**
5069   * free_pages_exact - release memory allocated via alloc_pages_exact()
5070   * @virt: the value returned by alloc_pages_exact.
5071   * @size: size of allocation, same value as passed to alloc_pages_exact().
5072   *
5073   * Release the memory allocated by a previous call to alloc_pages_exact.
5074   */
free_pages_exact(void * virt,size_t size)5075  void free_pages_exact(void *virt, size_t size)
5076  {
5077  	unsigned long addr = (unsigned long)virt;
5078  	unsigned long end = addr + PAGE_ALIGN(size);
5079  
5080  	while (addr < end) {
5081  		free_page(addr);
5082  		addr += PAGE_SIZE;
5083  	}
5084  }
5085  EXPORT_SYMBOL(free_pages_exact);
5086  
5087  /**
5088   * nr_free_zone_pages - count number of pages beyond high watermark
5089   * @offset: The zone index of the highest zone
5090   *
5091   * nr_free_zone_pages() counts the number of pages which are beyond the
5092   * high watermark within all zones at or below a given zone index.  For each
5093   * zone, the number of pages is calculated as:
5094   *
5095   *     nr_free_zone_pages = managed_pages - high_pages
5096   *
5097   * Return: number of pages beyond high watermark.
5098   */
nr_free_zone_pages(int offset)5099  static unsigned long nr_free_zone_pages(int offset)
5100  {
5101  	struct zoneref *z;
5102  	struct zone *zone;
5103  
5104  	/* Just pick one node, since fallback list is circular */
5105  	unsigned long sum = 0;
5106  
5107  	struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
5108  
5109  	for_each_zone_zonelist(zone, z, zonelist, offset) {
5110  		unsigned long size = zone_managed_pages(zone);
5111  		unsigned long high = high_wmark_pages(zone);
5112  		if (size > high)
5113  			sum += size - high;
5114  	}
5115  
5116  	return sum;
5117  }
5118  
5119  /**
5120   * nr_free_buffer_pages - count number of pages beyond high watermark
5121   *
5122   * nr_free_buffer_pages() counts the number of pages which are beyond the high
5123   * watermark within ZONE_DMA and ZONE_NORMAL.
5124   *
5125   * Return: number of pages beyond high watermark within ZONE_DMA and
5126   * ZONE_NORMAL.
5127   */
nr_free_buffer_pages(void)5128  unsigned long nr_free_buffer_pages(void)
5129  {
5130  	return nr_free_zone_pages(gfp_zone(GFP_USER));
5131  }
5132  EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
5133  
zoneref_set_zone(struct zone * zone,struct zoneref * zoneref)5134  static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
5135  {
5136  	zoneref->zone = zone;
5137  	zoneref->zone_idx = zone_idx(zone);
5138  }
5139  
5140  /*
5141   * Builds allocation fallback zone lists.
5142   *
5143   * Add all populated zones of a node to the zonelist.
5144   */
build_zonerefs_node(pg_data_t * pgdat,struct zoneref * zonerefs)5145  static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs)
5146  {
5147  	struct zone *zone;
5148  	enum zone_type zone_type = MAX_NR_ZONES;
5149  	int nr_zones = 0;
5150  
5151  	do {
5152  		zone_type--;
5153  		zone = pgdat->node_zones + zone_type;
5154  		if (populated_zone(zone)) {
5155  			zoneref_set_zone(zone, &zonerefs[nr_zones++]);
5156  			check_highest_zone(zone_type);
5157  		}
5158  	} while (zone_type);
5159  
5160  	return nr_zones;
5161  }
5162  
5163  #ifdef CONFIG_NUMA
5164  
__parse_numa_zonelist_order(char * s)5165  static int __parse_numa_zonelist_order(char *s)
5166  {
5167  	/*
5168  	 * We used to support different zonelists modes but they turned
5169  	 * out to be just not useful. Let's keep the warning in place
5170  	 * if somebody still use the cmd line parameter so that we do
5171  	 * not fail it silently
5172  	 */
5173  	if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) {
5174  		pr_warn("Ignoring unsupported numa_zonelist_order value:  %s\n", s);
5175  		return -EINVAL;
5176  	}
5177  	return 0;
5178  }
5179  
5180  static char numa_zonelist_order[] = "Node";
5181  #define NUMA_ZONELIST_ORDER_LEN	16
5182  /*
5183   * sysctl handler for numa_zonelist_order
5184   */
numa_zonelist_order_handler(const struct ctl_table * table,int write,void * buffer,size_t * length,loff_t * ppos)5185  static int numa_zonelist_order_handler(const struct ctl_table *table, int write,
5186  		void *buffer, size_t *length, loff_t *ppos)
5187  {
5188  	if (write)
5189  		return __parse_numa_zonelist_order(buffer);
5190  	return proc_dostring(table, write, buffer, length, ppos);
5191  }
5192  
5193  static int node_load[MAX_NUMNODES];
5194  
5195  /**
5196   * find_next_best_node - find the next node that should appear in a given node's fallback list
5197   * @node: node whose fallback list we're appending
5198   * @used_node_mask: nodemask_t of already used nodes
5199   *
5200   * We use a number of factors to determine which is the next node that should
5201   * appear on a given node's fallback list.  The node should not have appeared
5202   * already in @node's fallback list, and it should be the next closest node
5203   * according to the distance array (which contains arbitrary distance values
5204   * from each node to each node in the system), and should also prefer nodes
5205   * with no CPUs, since presumably they'll have very little allocation pressure
5206   * on them otherwise.
5207   *
5208   * Return: node id of the found node or %NUMA_NO_NODE if no node is found.
5209   */
find_next_best_node(int node,nodemask_t * used_node_mask)5210  int find_next_best_node(int node, nodemask_t *used_node_mask)
5211  {
5212  	int n, val;
5213  	int min_val = INT_MAX;
5214  	int best_node = NUMA_NO_NODE;
5215  
5216  	/*
5217  	 * Use the local node if we haven't already, but for memoryless local
5218  	 * node, we should skip it and fall back to other nodes.
5219  	 */
5220  	if (!node_isset(node, *used_node_mask) && node_state(node, N_MEMORY)) {
5221  		node_set(node, *used_node_mask);
5222  		return node;
5223  	}
5224  
5225  	for_each_node_state(n, N_MEMORY) {
5226  
5227  		/* Don't want a node to appear more than once */
5228  		if (node_isset(n, *used_node_mask))
5229  			continue;
5230  
5231  		/* Use the distance array to find the distance */
5232  		val = node_distance(node, n);
5233  
5234  		/* Penalize nodes under us ("prefer the next node") */
5235  		val += (n < node);
5236  
5237  		/* Give preference to headless and unused nodes */
5238  		if (!cpumask_empty(cpumask_of_node(n)))
5239  			val += PENALTY_FOR_NODE_WITH_CPUS;
5240  
5241  		/* Slight preference for less loaded node */
5242  		val *= MAX_NUMNODES;
5243  		val += node_load[n];
5244  
5245  		if (val < min_val) {
5246  			min_val = val;
5247  			best_node = n;
5248  		}
5249  	}
5250  
5251  	if (best_node >= 0)
5252  		node_set(best_node, *used_node_mask);
5253  
5254  	return best_node;
5255  }
5256  
5257  
5258  /*
5259   * Build zonelists ordered by node and zones within node.
5260   * This results in maximum locality--normal zone overflows into local
5261   * DMA zone, if any--but risks exhausting DMA zone.
5262   */
build_zonelists_in_node_order(pg_data_t * pgdat,int * node_order,unsigned nr_nodes)5263  static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
5264  		unsigned nr_nodes)
5265  {
5266  	struct zoneref *zonerefs;
5267  	int i;
5268  
5269  	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
5270  
5271  	for (i = 0; i < nr_nodes; i++) {
5272  		int nr_zones;
5273  
5274  		pg_data_t *node = NODE_DATA(node_order[i]);
5275  
5276  		nr_zones = build_zonerefs_node(node, zonerefs);
5277  		zonerefs += nr_zones;
5278  	}
5279  	zonerefs->zone = NULL;
5280  	zonerefs->zone_idx = 0;
5281  }
5282  
5283  /*
5284   * Build __GFP_THISNODE zonelists
5285   */
build_thisnode_zonelists(pg_data_t * pgdat)5286  static void build_thisnode_zonelists(pg_data_t *pgdat)
5287  {
5288  	struct zoneref *zonerefs;
5289  	int nr_zones;
5290  
5291  	zonerefs = pgdat->node_zonelists[ZONELIST_NOFALLBACK]._zonerefs;
5292  	nr_zones = build_zonerefs_node(pgdat, zonerefs);
5293  	zonerefs += nr_zones;
5294  	zonerefs->zone = NULL;
5295  	zonerefs->zone_idx = 0;
5296  }
5297  
5298  /*
5299   * Build zonelists ordered by zone and nodes within zones.
5300   * This results in conserving DMA zone[s] until all Normal memory is
5301   * exhausted, but results in overflowing to remote node while memory
5302   * may still exist in local DMA zone.
5303   */
5304  
build_zonelists(pg_data_t * pgdat)5305  static void build_zonelists(pg_data_t *pgdat)
5306  {
5307  	static int node_order[MAX_NUMNODES];
5308  	int node, nr_nodes = 0;
5309  	nodemask_t used_mask = NODE_MASK_NONE;
5310  	int local_node, prev_node;
5311  
5312  	/* NUMA-aware ordering of nodes */
5313  	local_node = pgdat->node_id;
5314  	prev_node = local_node;
5315  
5316  	memset(node_order, 0, sizeof(node_order));
5317  	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
5318  		/*
5319  		 * We don't want to pressure a particular node.
5320  		 * So adding penalty to the first node in same
5321  		 * distance group to make it round-robin.
5322  		 */
5323  		if (node_distance(local_node, node) !=
5324  		    node_distance(local_node, prev_node))
5325  			node_load[node] += 1;
5326  
5327  		node_order[nr_nodes++] = node;
5328  		prev_node = node;
5329  	}
5330  
5331  	build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
5332  	build_thisnode_zonelists(pgdat);
5333  	pr_info("Fallback order for Node %d: ", local_node);
5334  	for (node = 0; node < nr_nodes; node++)
5335  		pr_cont("%d ", node_order[node]);
5336  	pr_cont("\n");
5337  }
5338  
5339  #ifdef CONFIG_HAVE_MEMORYLESS_NODES
5340  /*
5341   * Return node id of node used for "local" allocations.
5342   * I.e., first node id of first zone in arg node's generic zonelist.
5343   * Used for initializing percpu 'numa_mem', which is used primarily
5344   * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
5345   */
local_memory_node(int node)5346  int local_memory_node(int node)
5347  {
5348  	struct zoneref *z;
5349  
5350  	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
5351  				   gfp_zone(GFP_KERNEL),
5352  				   NULL);
5353  	return zonelist_node_idx(z);
5354  }
5355  #endif
5356  
5357  static void setup_min_unmapped_ratio(void);
5358  static void setup_min_slab_ratio(void);
5359  #else	/* CONFIG_NUMA */
5360  
build_zonelists(pg_data_t * pgdat)5361  static void build_zonelists(pg_data_t *pgdat)
5362  {
5363  	struct zoneref *zonerefs;
5364  	int nr_zones;
5365  
5366  	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
5367  	nr_zones = build_zonerefs_node(pgdat, zonerefs);
5368  	zonerefs += nr_zones;
5369  
5370  	zonerefs->zone = NULL;
5371  	zonerefs->zone_idx = 0;
5372  }
5373  
5374  #endif	/* CONFIG_NUMA */
5375  
5376  /*
5377   * Boot pageset table. One per cpu which is going to be used for all
5378   * zones and all nodes. The parameters will be set in such a way
5379   * that an item put on a list will immediately be handed over to
5380   * the buddy list. This is safe since pageset manipulation is done
5381   * with interrupts disabled.
5382   *
5383   * The boot_pagesets must be kept even after bootup is complete for
5384   * unused processors and/or zones. They do play a role for bootstrapping
5385   * hotplugged processors.
5386   *
5387   * zoneinfo_show() and maybe other functions do
5388   * not check if the processor is online before following the pageset pointer.
5389   * Other parts of the kernel may not check if the zone is available.
5390   */
5391  static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats);
5392  /* These effectively disable the pcplists in the boot pageset completely */
5393  #define BOOT_PAGESET_HIGH	0
5394  #define BOOT_PAGESET_BATCH	1
5395  static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
5396  static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
5397  
__build_all_zonelists(void * data)5398  static void __build_all_zonelists(void *data)
5399  {
5400  	int nid;
5401  	int __maybe_unused cpu;
5402  	pg_data_t *self = data;
5403  	unsigned long flags;
5404  
5405  	/*
5406  	 * The zonelist_update_seq must be acquired with irqsave because the
5407  	 * reader can be invoked from IRQ with GFP_ATOMIC.
5408  	 */
5409  	write_seqlock_irqsave(&zonelist_update_seq, flags);
5410  	/*
5411  	 * Also disable synchronous printk() to prevent any printk() from
5412  	 * trying to hold port->lock, for
5413  	 * tty_insert_flip_string_and_push_buffer() on other CPU might be
5414  	 * calling kmalloc(GFP_ATOMIC | __GFP_NOWARN) with port->lock held.
5415  	 */
5416  	printk_deferred_enter();
5417  
5418  #ifdef CONFIG_NUMA
5419  	memset(node_load, 0, sizeof(node_load));
5420  #endif
5421  
5422  	/*
5423  	 * This node is hotadded and no memory is yet present.   So just
5424  	 * building zonelists is fine - no need to touch other nodes.
5425  	 */
5426  	if (self && !node_online(self->node_id)) {
5427  		build_zonelists(self);
5428  	} else {
5429  		/*
5430  		 * All possible nodes have pgdat preallocated
5431  		 * in free_area_init
5432  		 */
5433  		for_each_node(nid) {
5434  			pg_data_t *pgdat = NODE_DATA(nid);
5435  
5436  			build_zonelists(pgdat);
5437  		}
5438  
5439  #ifdef CONFIG_HAVE_MEMORYLESS_NODES
5440  		/*
5441  		 * We now know the "local memory node" for each node--
5442  		 * i.e., the node of the first zone in the generic zonelist.
5443  		 * Set up numa_mem percpu variable for on-line cpus.  During
5444  		 * boot, only the boot cpu should be on-line;  we'll init the
5445  		 * secondary cpus' numa_mem as they come on-line.  During
5446  		 * node/memory hotplug, we'll fixup all on-line cpus.
5447  		 */
5448  		for_each_online_cpu(cpu)
5449  			set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
5450  #endif
5451  	}
5452  
5453  	printk_deferred_exit();
5454  	write_sequnlock_irqrestore(&zonelist_update_seq, flags);
5455  }
5456  
5457  static noinline void __init
build_all_zonelists_init(void)5458  build_all_zonelists_init(void)
5459  {
5460  	int cpu;
5461  
5462  	__build_all_zonelists(NULL);
5463  
5464  	/*
5465  	 * Initialize the boot_pagesets that are going to be used
5466  	 * for bootstrapping processors. The real pagesets for
5467  	 * each zone will be allocated later when the per cpu
5468  	 * allocator is available.
5469  	 *
5470  	 * boot_pagesets are used also for bootstrapping offline
5471  	 * cpus if the system is already booted because the pagesets
5472  	 * are needed to initialize allocators on a specific cpu too.
5473  	 * F.e. the percpu allocator needs the page allocator which
5474  	 * needs the percpu allocator in order to allocate its pagesets
5475  	 * (a chicken-egg dilemma).
5476  	 */
5477  	for_each_possible_cpu(cpu)
5478  		per_cpu_pages_init(&per_cpu(boot_pageset, cpu), &per_cpu(boot_zonestats, cpu));
5479  
5480  	mminit_verify_zonelist();
5481  	cpuset_init_current_mems_allowed();
5482  }
5483  
5484  /*
5485   * unless system_state == SYSTEM_BOOTING.
5486   *
5487   * __ref due to call of __init annotated helper build_all_zonelists_init
5488   * [protected by SYSTEM_BOOTING].
5489   */
build_all_zonelists(pg_data_t * pgdat)5490  void __ref build_all_zonelists(pg_data_t *pgdat)
5491  {
5492  	unsigned long vm_total_pages;
5493  
5494  	if (system_state == SYSTEM_BOOTING) {
5495  		build_all_zonelists_init();
5496  	} else {
5497  		__build_all_zonelists(pgdat);
5498  		/* cpuset refresh routine should be here */
5499  	}
5500  	/* Get the number of free pages beyond high watermark in all zones. */
5501  	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
5502  	/*
5503  	 * Disable grouping by mobility if the number of pages in the
5504  	 * system is too low to allow the mechanism to work. It would be
5505  	 * more accurate, but expensive to check per-zone. This check is
5506  	 * made on memory-hotadd so a system can start with mobility
5507  	 * disabled and enable it later
5508  	 */
5509  	if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
5510  		page_group_by_mobility_disabled = 1;
5511  	else
5512  		page_group_by_mobility_disabled = 0;
5513  
5514  	pr_info("Built %u zonelists, mobility grouping %s.  Total pages: %ld\n",
5515  		nr_online_nodes,
5516  		page_group_by_mobility_disabled ? "off" : "on",
5517  		vm_total_pages);
5518  #ifdef CONFIG_NUMA
5519  	pr_info("Policy zone: %s\n", zone_names[policy_zone]);
5520  #endif
5521  }
5522  
zone_batchsize(struct zone * zone)5523  static int zone_batchsize(struct zone *zone)
5524  {
5525  #ifdef CONFIG_MMU
5526  	int batch;
5527  
5528  	/*
5529  	 * The number of pages to batch allocate is either ~0.1%
5530  	 * of the zone or 1MB, whichever is smaller. The batch
5531  	 * size is striking a balance between allocation latency
5532  	 * and zone lock contention.
5533  	 */
5534  	batch = min(zone_managed_pages(zone) >> 10, SZ_1M / PAGE_SIZE);
5535  	batch /= 4;		/* We effectively *= 4 below */
5536  	if (batch < 1)
5537  		batch = 1;
5538  
5539  	/*
5540  	 * Clamp the batch to a 2^n - 1 value. Having a power
5541  	 * of 2 value was found to be more likely to have
5542  	 * suboptimal cache aliasing properties in some cases.
5543  	 *
5544  	 * For example if 2 tasks are alternately allocating
5545  	 * batches of pages, one task can end up with a lot
5546  	 * of pages of one half of the possible page colors
5547  	 * and the other with pages of the other colors.
5548  	 */
5549  	batch = rounddown_pow_of_two(batch + batch/2) - 1;
5550  
5551  	return batch;
5552  
5553  #else
5554  	/* The deferral and batching of frees should be suppressed under NOMMU
5555  	 * conditions.
5556  	 *
5557  	 * The problem is that NOMMU needs to be able to allocate large chunks
5558  	 * of contiguous memory as there's no hardware page translation to
5559  	 * assemble apparent contiguous memory from discontiguous pages.
5560  	 *
5561  	 * Queueing large contiguous runs of pages for batching, however,
5562  	 * causes the pages to actually be freed in smaller chunks.  As there
5563  	 * can be a significant delay between the individual batches being
5564  	 * recycled, this leads to the once large chunks of space being
5565  	 * fragmented and becoming unavailable for high-order allocations.
5566  	 */
5567  	return 0;
5568  #endif
5569  }
5570  
5571  static int percpu_pagelist_high_fraction;
zone_highsize(struct zone * zone,int batch,int cpu_online,int high_fraction)5572  static int zone_highsize(struct zone *zone, int batch, int cpu_online,
5573  			 int high_fraction)
5574  {
5575  #ifdef CONFIG_MMU
5576  	int high;
5577  	int nr_split_cpus;
5578  	unsigned long total_pages;
5579  
5580  	if (!high_fraction) {
5581  		/*
5582  		 * By default, the high value of the pcp is based on the zone
5583  		 * low watermark so that if they are full then background
5584  		 * reclaim will not be started prematurely.
5585  		 */
5586  		total_pages = low_wmark_pages(zone);
5587  	} else {
5588  		/*
5589  		 * If percpu_pagelist_high_fraction is configured, the high
5590  		 * value is based on a fraction of the managed pages in the
5591  		 * zone.
5592  		 */
5593  		total_pages = zone_managed_pages(zone) / high_fraction;
5594  	}
5595  
5596  	/*
5597  	 * Split the high value across all online CPUs local to the zone. Note
5598  	 * that early in boot that CPUs may not be online yet and that during
5599  	 * CPU hotplug that the cpumask is not yet updated when a CPU is being
5600  	 * onlined. For memory nodes that have no CPUs, split the high value
5601  	 * across all online CPUs to mitigate the risk that reclaim is triggered
5602  	 * prematurely due to pages stored on pcp lists.
5603  	 */
5604  	nr_split_cpus = cpumask_weight(cpumask_of_node(zone_to_nid(zone))) + cpu_online;
5605  	if (!nr_split_cpus)
5606  		nr_split_cpus = num_online_cpus();
5607  	high = total_pages / nr_split_cpus;
5608  
5609  	/*
5610  	 * Ensure high is at least batch*4. The multiple is based on the
5611  	 * historical relationship between high and batch.
5612  	 */
5613  	high = max(high, batch << 2);
5614  
5615  	return high;
5616  #else
5617  	return 0;
5618  #endif
5619  }
5620  
5621  /*
5622   * pcp->high and pcp->batch values are related and generally batch is lower
5623   * than high. They are also related to pcp->count such that count is lower
5624   * than high, and as soon as it reaches high, the pcplist is flushed.
5625   *
5626   * However, guaranteeing these relations at all times would require e.g. write
5627   * barriers here but also careful usage of read barriers at the read side, and
5628   * thus be prone to error and bad for performance. Thus the update only prevents
5629   * store tearing. Any new users of pcp->batch, pcp->high_min and pcp->high_max
5630   * should ensure they can cope with those fields changing asynchronously, and
5631   * fully trust only the pcp->count field on the local CPU with interrupts
5632   * disabled.
5633   *
5634   * mutex_is_locked(&pcp_batch_high_lock) required when calling this function
5635   * outside of boot time (or some other assurance that no concurrent updaters
5636   * exist).
5637   */
pageset_update(struct per_cpu_pages * pcp,unsigned long high_min,unsigned long high_max,unsigned long batch)5638  static void pageset_update(struct per_cpu_pages *pcp, unsigned long high_min,
5639  			   unsigned long high_max, unsigned long batch)
5640  {
5641  	WRITE_ONCE(pcp->batch, batch);
5642  	WRITE_ONCE(pcp->high_min, high_min);
5643  	WRITE_ONCE(pcp->high_max, high_max);
5644  }
5645  
per_cpu_pages_init(struct per_cpu_pages * pcp,struct per_cpu_zonestat * pzstats)5646  static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats)
5647  {
5648  	int pindex;
5649  
5650  	memset(pcp, 0, sizeof(*pcp));
5651  	memset(pzstats, 0, sizeof(*pzstats));
5652  
5653  	spin_lock_init(&pcp->lock);
5654  	for (pindex = 0; pindex < NR_PCP_LISTS; pindex++)
5655  		INIT_LIST_HEAD(&pcp->lists[pindex]);
5656  
5657  	/*
5658  	 * Set batch and high values safe for a boot pageset. A true percpu
5659  	 * pageset's initialization will update them subsequently. Here we don't
5660  	 * need to be as careful as pageset_update() as nobody can access the
5661  	 * pageset yet.
5662  	 */
5663  	pcp->high_min = BOOT_PAGESET_HIGH;
5664  	pcp->high_max = BOOT_PAGESET_HIGH;
5665  	pcp->batch = BOOT_PAGESET_BATCH;
5666  	pcp->free_count = 0;
5667  }
5668  
__zone_set_pageset_high_and_batch(struct zone * zone,unsigned long high_min,unsigned long high_max,unsigned long batch)5669  static void __zone_set_pageset_high_and_batch(struct zone *zone, unsigned long high_min,
5670  					      unsigned long high_max, unsigned long batch)
5671  {
5672  	struct per_cpu_pages *pcp;
5673  	int cpu;
5674  
5675  	for_each_possible_cpu(cpu) {
5676  		pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
5677  		pageset_update(pcp, high_min, high_max, batch);
5678  	}
5679  }
5680  
5681  /*
5682   * Calculate and set new high and batch values for all per-cpu pagesets of a
5683   * zone based on the zone's size.
5684   */
zone_set_pageset_high_and_batch(struct zone * zone,int cpu_online)5685  static void zone_set_pageset_high_and_batch(struct zone *zone, int cpu_online)
5686  {
5687  	int new_high_min, new_high_max, new_batch;
5688  
5689  	new_batch = max(1, zone_batchsize(zone));
5690  	if (percpu_pagelist_high_fraction) {
5691  		new_high_min = zone_highsize(zone, new_batch, cpu_online,
5692  					     percpu_pagelist_high_fraction);
5693  		/*
5694  		 * PCP high is tuned manually, disable auto-tuning via
5695  		 * setting high_min and high_max to the manual value.
5696  		 */
5697  		new_high_max = new_high_min;
5698  	} else {
5699  		new_high_min = zone_highsize(zone, new_batch, cpu_online, 0);
5700  		new_high_max = zone_highsize(zone, new_batch, cpu_online,
5701  					     MIN_PERCPU_PAGELIST_HIGH_FRACTION);
5702  	}
5703  
5704  	if (zone->pageset_high_min == new_high_min &&
5705  	    zone->pageset_high_max == new_high_max &&
5706  	    zone->pageset_batch == new_batch)
5707  		return;
5708  
5709  	zone->pageset_high_min = new_high_min;
5710  	zone->pageset_high_max = new_high_max;
5711  	zone->pageset_batch = new_batch;
5712  
5713  	__zone_set_pageset_high_and_batch(zone, new_high_min, new_high_max,
5714  					  new_batch);
5715  }
5716  
setup_zone_pageset(struct zone * zone)5717  void __meminit setup_zone_pageset(struct zone *zone)
5718  {
5719  	int cpu;
5720  
5721  	/* Size may be 0 on !SMP && !NUMA */
5722  	if (sizeof(struct per_cpu_zonestat) > 0)
5723  		zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat);
5724  
5725  	zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages);
5726  	for_each_possible_cpu(cpu) {
5727  		struct per_cpu_pages *pcp;
5728  		struct per_cpu_zonestat *pzstats;
5729  
5730  		pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
5731  		pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
5732  		per_cpu_pages_init(pcp, pzstats);
5733  	}
5734  
5735  	zone_set_pageset_high_and_batch(zone, 0);
5736  }
5737  
5738  /*
5739   * The zone indicated has a new number of managed_pages; batch sizes and percpu
5740   * page high values need to be recalculated.
5741   */
zone_pcp_update(struct zone * zone,int cpu_online)5742  static void zone_pcp_update(struct zone *zone, int cpu_online)
5743  {
5744  	mutex_lock(&pcp_batch_high_lock);
5745  	zone_set_pageset_high_and_batch(zone, cpu_online);
5746  	mutex_unlock(&pcp_batch_high_lock);
5747  }
5748  
zone_pcp_update_cacheinfo(struct zone * zone,unsigned int cpu)5749  static void zone_pcp_update_cacheinfo(struct zone *zone, unsigned int cpu)
5750  {
5751  	struct per_cpu_pages *pcp;
5752  	struct cpu_cacheinfo *cci;
5753  
5754  	pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
5755  	cci = get_cpu_cacheinfo(cpu);
5756  	/*
5757  	 * If data cache slice of CPU is large enough, "pcp->batch"
5758  	 * pages can be preserved in PCP before draining PCP for
5759  	 * consecutive high-order pages freeing without allocation.
5760  	 * This can reduce zone lock contention without hurting
5761  	 * cache-hot pages sharing.
5762  	 */
5763  	spin_lock(&pcp->lock);
5764  	if ((cci->per_cpu_data_slice_size >> PAGE_SHIFT) > 3 * pcp->batch)
5765  		pcp->flags |= PCPF_FREE_HIGH_BATCH;
5766  	else
5767  		pcp->flags &= ~PCPF_FREE_HIGH_BATCH;
5768  	spin_unlock(&pcp->lock);
5769  }
5770  
setup_pcp_cacheinfo(unsigned int cpu)5771  void setup_pcp_cacheinfo(unsigned int cpu)
5772  {
5773  	struct zone *zone;
5774  
5775  	for_each_populated_zone(zone)
5776  		zone_pcp_update_cacheinfo(zone, cpu);
5777  }
5778  
5779  /*
5780   * Allocate per cpu pagesets and initialize them.
5781   * Before this call only boot pagesets were available.
5782   */
setup_per_cpu_pageset(void)5783  void __init setup_per_cpu_pageset(void)
5784  {
5785  	struct pglist_data *pgdat;
5786  	struct zone *zone;
5787  	int __maybe_unused cpu;
5788  
5789  	for_each_populated_zone(zone)
5790  		setup_zone_pageset(zone);
5791  
5792  #ifdef CONFIG_NUMA
5793  	/*
5794  	 * Unpopulated zones continue using the boot pagesets.
5795  	 * The numa stats for these pagesets need to be reset.
5796  	 * Otherwise, they will end up skewing the stats of
5797  	 * the nodes these zones are associated with.
5798  	 */
5799  	for_each_possible_cpu(cpu) {
5800  		struct per_cpu_zonestat *pzstats = &per_cpu(boot_zonestats, cpu);
5801  		memset(pzstats->vm_numa_event, 0,
5802  		       sizeof(pzstats->vm_numa_event));
5803  	}
5804  #endif
5805  
5806  	for_each_online_pgdat(pgdat)
5807  		pgdat->per_cpu_nodestats =
5808  			alloc_percpu(struct per_cpu_nodestat);
5809  }
5810  
zone_pcp_init(struct zone * zone)5811  __meminit void zone_pcp_init(struct zone *zone)
5812  {
5813  	/*
5814  	 * per cpu subsystem is not up at this point. The following code
5815  	 * relies on the ability of the linker to provide the
5816  	 * offset of a (static) per cpu variable into the per cpu area.
5817  	 */
5818  	zone->per_cpu_pageset = &boot_pageset;
5819  	zone->per_cpu_zonestats = &boot_zonestats;
5820  	zone->pageset_high_min = BOOT_PAGESET_HIGH;
5821  	zone->pageset_high_max = BOOT_PAGESET_HIGH;
5822  	zone->pageset_batch = BOOT_PAGESET_BATCH;
5823  
5824  	if (populated_zone(zone))
5825  		pr_debug("  %s zone: %lu pages, LIFO batch:%u\n", zone->name,
5826  			 zone->present_pages, zone_batchsize(zone));
5827  }
5828  
adjust_managed_page_count(struct page * page,long count)5829  void adjust_managed_page_count(struct page *page, long count)
5830  {
5831  	atomic_long_add(count, &page_zone(page)->managed_pages);
5832  	totalram_pages_add(count);
5833  }
5834  EXPORT_SYMBOL(adjust_managed_page_count);
5835  
free_reserved_area(void * start,void * end,int poison,const char * s)5836  unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
5837  {
5838  	void *pos;
5839  	unsigned long pages = 0;
5840  
5841  	start = (void *)PAGE_ALIGN((unsigned long)start);
5842  	end = (void *)((unsigned long)end & PAGE_MASK);
5843  	for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
5844  		struct page *page = virt_to_page(pos);
5845  		void *direct_map_addr;
5846  
5847  		/*
5848  		 * 'direct_map_addr' might be different from 'pos'
5849  		 * because some architectures' virt_to_page()
5850  		 * work with aliases.  Getting the direct map
5851  		 * address ensures that we get a _writeable_
5852  		 * alias for the memset().
5853  		 */
5854  		direct_map_addr = page_address(page);
5855  		/*
5856  		 * Perform a kasan-unchecked memset() since this memory
5857  		 * has not been initialized.
5858  		 */
5859  		direct_map_addr = kasan_reset_tag(direct_map_addr);
5860  		if ((unsigned int)poison <= 0xFF)
5861  			memset(direct_map_addr, poison, PAGE_SIZE);
5862  
5863  		free_reserved_page(page);
5864  	}
5865  
5866  	if (pages && s)
5867  		pr_info("Freeing %s memory: %ldK\n", s, K(pages));
5868  
5869  	return pages;
5870  }
5871  
free_reserved_page(struct page * page)5872  void free_reserved_page(struct page *page)
5873  {
5874  	clear_page_tag_ref(page);
5875  	ClearPageReserved(page);
5876  	init_page_count(page);
5877  	__free_page(page);
5878  	adjust_managed_page_count(page, 1);
5879  }
5880  EXPORT_SYMBOL(free_reserved_page);
5881  
page_alloc_cpu_dead(unsigned int cpu)5882  static int page_alloc_cpu_dead(unsigned int cpu)
5883  {
5884  	struct zone *zone;
5885  
5886  	lru_add_drain_cpu(cpu);
5887  	mlock_drain_remote(cpu);
5888  	drain_pages(cpu);
5889  
5890  	/*
5891  	 * Spill the event counters of the dead processor
5892  	 * into the current processors event counters.
5893  	 * This artificially elevates the count of the current
5894  	 * processor.
5895  	 */
5896  	vm_events_fold_cpu(cpu);
5897  
5898  	/*
5899  	 * Zero the differential counters of the dead processor
5900  	 * so that the vm statistics are consistent.
5901  	 *
5902  	 * This is only okay since the processor is dead and cannot
5903  	 * race with what we are doing.
5904  	 */
5905  	cpu_vm_stats_fold(cpu);
5906  
5907  	for_each_populated_zone(zone)
5908  		zone_pcp_update(zone, 0);
5909  
5910  	return 0;
5911  }
5912  
page_alloc_cpu_online(unsigned int cpu)5913  static int page_alloc_cpu_online(unsigned int cpu)
5914  {
5915  	struct zone *zone;
5916  
5917  	for_each_populated_zone(zone)
5918  		zone_pcp_update(zone, 1);
5919  	return 0;
5920  }
5921  
page_alloc_init_cpuhp(void)5922  void __init page_alloc_init_cpuhp(void)
5923  {
5924  	int ret;
5925  
5926  	ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC,
5927  					"mm/page_alloc:pcp",
5928  					page_alloc_cpu_online,
5929  					page_alloc_cpu_dead);
5930  	WARN_ON(ret < 0);
5931  }
5932  
5933  /*
5934   * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
5935   *	or min_free_kbytes changes.
5936   */
calculate_totalreserve_pages(void)5937  static void calculate_totalreserve_pages(void)
5938  {
5939  	struct pglist_data *pgdat;
5940  	unsigned long reserve_pages = 0;
5941  	enum zone_type i, j;
5942  
5943  	for_each_online_pgdat(pgdat) {
5944  
5945  		pgdat->totalreserve_pages = 0;
5946  
5947  		for (i = 0; i < MAX_NR_ZONES; i++) {
5948  			struct zone *zone = pgdat->node_zones + i;
5949  			long max = 0;
5950  			unsigned long managed_pages = zone_managed_pages(zone);
5951  
5952  			/* Find valid and maximum lowmem_reserve in the zone */
5953  			for (j = i; j < MAX_NR_ZONES; j++) {
5954  				if (zone->lowmem_reserve[j] > max)
5955  					max = zone->lowmem_reserve[j];
5956  			}
5957  
5958  			/* we treat the high watermark as reserved pages. */
5959  			max += high_wmark_pages(zone);
5960  
5961  			if (max > managed_pages)
5962  				max = managed_pages;
5963  
5964  			pgdat->totalreserve_pages += max;
5965  
5966  			reserve_pages += max;
5967  		}
5968  	}
5969  	totalreserve_pages = reserve_pages;
5970  }
5971  
5972  /*
5973   * setup_per_zone_lowmem_reserve - called whenever
5974   *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
5975   *	has a correct pages reserved value, so an adequate number of
5976   *	pages are left in the zone after a successful __alloc_pages().
5977   */
setup_per_zone_lowmem_reserve(void)5978  static void setup_per_zone_lowmem_reserve(void)
5979  {
5980  	struct pglist_data *pgdat;
5981  	enum zone_type i, j;
5982  
5983  	for_each_online_pgdat(pgdat) {
5984  		for (i = 0; i < MAX_NR_ZONES - 1; i++) {
5985  			struct zone *zone = &pgdat->node_zones[i];
5986  			int ratio = sysctl_lowmem_reserve_ratio[i];
5987  			bool clear = !ratio || !zone_managed_pages(zone);
5988  			unsigned long managed_pages = 0;
5989  
5990  			for (j = i + 1; j < MAX_NR_ZONES; j++) {
5991  				struct zone *upper_zone = &pgdat->node_zones[j];
5992  				bool empty = !zone_managed_pages(upper_zone);
5993  
5994  				managed_pages += zone_managed_pages(upper_zone);
5995  
5996  				if (clear || empty)
5997  					zone->lowmem_reserve[j] = 0;
5998  				else
5999  					zone->lowmem_reserve[j] = managed_pages / ratio;
6000  			}
6001  		}
6002  	}
6003  
6004  	/* update totalreserve_pages */
6005  	calculate_totalreserve_pages();
6006  }
6007  
__setup_per_zone_wmarks(void)6008  static void __setup_per_zone_wmarks(void)
6009  {
6010  	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
6011  	unsigned long lowmem_pages = 0;
6012  	struct zone *zone;
6013  	unsigned long flags;
6014  
6015  	/* Calculate total number of !ZONE_HIGHMEM and !ZONE_MOVABLE pages */
6016  	for_each_zone(zone) {
6017  		if (!is_highmem(zone) && zone_idx(zone) != ZONE_MOVABLE)
6018  			lowmem_pages += zone_managed_pages(zone);
6019  	}
6020  
6021  	for_each_zone(zone) {
6022  		u64 tmp;
6023  
6024  		spin_lock_irqsave(&zone->lock, flags);
6025  		tmp = (u64)pages_min * zone_managed_pages(zone);
6026  		tmp = div64_ul(tmp, lowmem_pages);
6027  		if (is_highmem(zone) || zone_idx(zone) == ZONE_MOVABLE) {
6028  			/*
6029  			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
6030  			 * need highmem and movable zones pages, so cap pages_min
6031  			 * to a small  value here.
6032  			 *
6033  			 * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
6034  			 * deltas control async page reclaim, and so should
6035  			 * not be capped for highmem and movable zones.
6036  			 */
6037  			unsigned long min_pages;
6038  
6039  			min_pages = zone_managed_pages(zone) / 1024;
6040  			min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
6041  			zone->_watermark[WMARK_MIN] = min_pages;
6042  		} else {
6043  			/*
6044  			 * If it's a lowmem zone, reserve a number of pages
6045  			 * proportionate to the zone's size.
6046  			 */
6047  			zone->_watermark[WMARK_MIN] = tmp;
6048  		}
6049  
6050  		/*
6051  		 * Set the kswapd watermarks distance according to the
6052  		 * scale factor in proportion to available memory, but
6053  		 * ensure a minimum size on small systems.
6054  		 */
6055  		tmp = max_t(u64, tmp >> 2,
6056  			    mult_frac(zone_managed_pages(zone),
6057  				      watermark_scale_factor, 10000));
6058  
6059  		zone->watermark_boost = 0;
6060  		zone->_watermark[WMARK_LOW]  = min_wmark_pages(zone) + tmp;
6061  		zone->_watermark[WMARK_HIGH] = low_wmark_pages(zone) + tmp;
6062  		zone->_watermark[WMARK_PROMO] = high_wmark_pages(zone) + tmp;
6063  
6064  		spin_unlock_irqrestore(&zone->lock, flags);
6065  	}
6066  
6067  	/* update totalreserve_pages */
6068  	calculate_totalreserve_pages();
6069  }
6070  
6071  /**
6072   * setup_per_zone_wmarks - called when min_free_kbytes changes
6073   * or when memory is hot-{added|removed}
6074   *
6075   * Ensures that the watermark[min,low,high] values for each zone are set
6076   * correctly with respect to min_free_kbytes.
6077   */
setup_per_zone_wmarks(void)6078  void setup_per_zone_wmarks(void)
6079  {
6080  	struct zone *zone;
6081  	static DEFINE_SPINLOCK(lock);
6082  
6083  	spin_lock(&lock);
6084  	__setup_per_zone_wmarks();
6085  	spin_unlock(&lock);
6086  
6087  	/*
6088  	 * The watermark size have changed so update the pcpu batch
6089  	 * and high limits or the limits may be inappropriate.
6090  	 */
6091  	for_each_zone(zone)
6092  		zone_pcp_update(zone, 0);
6093  }
6094  
6095  /*
6096   * Initialise min_free_kbytes.
6097   *
6098   * For small machines we want it small (128k min).  For large machines
6099   * we want it large (256MB max).  But it is not linear, because network
6100   * bandwidth does not increase linearly with machine size.  We use
6101   *
6102   *	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
6103   *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
6104   *
6105   * which yields
6106   *
6107   * 16MB:	512k
6108   * 32MB:	724k
6109   * 64MB:	1024k
6110   * 128MB:	1448k
6111   * 256MB:	2048k
6112   * 512MB:	2896k
6113   * 1024MB:	4096k
6114   * 2048MB:	5792k
6115   * 4096MB:	8192k
6116   * 8192MB:	11584k
6117   * 16384MB:	16384k
6118   */
calculate_min_free_kbytes(void)6119  void calculate_min_free_kbytes(void)
6120  {
6121  	unsigned long lowmem_kbytes;
6122  	int new_min_free_kbytes;
6123  
6124  	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
6125  	new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
6126  
6127  	if (new_min_free_kbytes > user_min_free_kbytes)
6128  		min_free_kbytes = clamp(new_min_free_kbytes, 128, 262144);
6129  	else
6130  		pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
6131  				new_min_free_kbytes, user_min_free_kbytes);
6132  
6133  }
6134  
init_per_zone_wmark_min(void)6135  int __meminit init_per_zone_wmark_min(void)
6136  {
6137  	calculate_min_free_kbytes();
6138  	setup_per_zone_wmarks();
6139  	refresh_zone_stat_thresholds();
6140  	setup_per_zone_lowmem_reserve();
6141  
6142  #ifdef CONFIG_NUMA
6143  	setup_min_unmapped_ratio();
6144  	setup_min_slab_ratio();
6145  #endif
6146  
6147  	khugepaged_min_free_kbytes_update();
6148  
6149  	return 0;
6150  }
postcore_initcall(init_per_zone_wmark_min)6151  postcore_initcall(init_per_zone_wmark_min)
6152  
6153  /*
6154   * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
6155   *	that we can call two helper functions whenever min_free_kbytes
6156   *	changes.
6157   */
6158  static int min_free_kbytes_sysctl_handler(const struct ctl_table *table, int write,
6159  		void *buffer, size_t *length, loff_t *ppos)
6160  {
6161  	int rc;
6162  
6163  	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
6164  	if (rc)
6165  		return rc;
6166  
6167  	if (write) {
6168  		user_min_free_kbytes = min_free_kbytes;
6169  		setup_per_zone_wmarks();
6170  	}
6171  	return 0;
6172  }
6173  
watermark_scale_factor_sysctl_handler(const struct ctl_table * table,int write,void * buffer,size_t * length,loff_t * ppos)6174  static int watermark_scale_factor_sysctl_handler(const struct ctl_table *table, int write,
6175  		void *buffer, size_t *length, loff_t *ppos)
6176  {
6177  	int rc;
6178  
6179  	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
6180  	if (rc)
6181  		return rc;
6182  
6183  	if (write)
6184  		setup_per_zone_wmarks();
6185  
6186  	return 0;
6187  }
6188  
6189  #ifdef CONFIG_NUMA
setup_min_unmapped_ratio(void)6190  static void setup_min_unmapped_ratio(void)
6191  {
6192  	pg_data_t *pgdat;
6193  	struct zone *zone;
6194  
6195  	for_each_online_pgdat(pgdat)
6196  		pgdat->min_unmapped_pages = 0;
6197  
6198  	for_each_zone(zone)
6199  		zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
6200  						         sysctl_min_unmapped_ratio) / 100;
6201  }
6202  
6203  
sysctl_min_unmapped_ratio_sysctl_handler(const struct ctl_table * table,int write,void * buffer,size_t * length,loff_t * ppos)6204  static int sysctl_min_unmapped_ratio_sysctl_handler(const struct ctl_table *table, int write,
6205  		void *buffer, size_t *length, loff_t *ppos)
6206  {
6207  	int rc;
6208  
6209  	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
6210  	if (rc)
6211  		return rc;
6212  
6213  	setup_min_unmapped_ratio();
6214  
6215  	return 0;
6216  }
6217  
setup_min_slab_ratio(void)6218  static void setup_min_slab_ratio(void)
6219  {
6220  	pg_data_t *pgdat;
6221  	struct zone *zone;
6222  
6223  	for_each_online_pgdat(pgdat)
6224  		pgdat->min_slab_pages = 0;
6225  
6226  	for_each_zone(zone)
6227  		zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
6228  						     sysctl_min_slab_ratio) / 100;
6229  }
6230  
sysctl_min_slab_ratio_sysctl_handler(const struct ctl_table * table,int write,void * buffer,size_t * length,loff_t * ppos)6231  static int sysctl_min_slab_ratio_sysctl_handler(const struct ctl_table *table, int write,
6232  		void *buffer, size_t *length, loff_t *ppos)
6233  {
6234  	int rc;
6235  
6236  	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
6237  	if (rc)
6238  		return rc;
6239  
6240  	setup_min_slab_ratio();
6241  
6242  	return 0;
6243  }
6244  #endif
6245  
6246  /*
6247   * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
6248   *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
6249   *	whenever sysctl_lowmem_reserve_ratio changes.
6250   *
6251   * The reserve ratio obviously has absolutely no relation with the
6252   * minimum watermarks. The lowmem reserve ratio can only make sense
6253   * if in function of the boot time zone sizes.
6254   */
lowmem_reserve_ratio_sysctl_handler(const struct ctl_table * table,int write,void * buffer,size_t * length,loff_t * ppos)6255  static int lowmem_reserve_ratio_sysctl_handler(const struct ctl_table *table,
6256  		int write, void *buffer, size_t *length, loff_t *ppos)
6257  {
6258  	int i;
6259  
6260  	proc_dointvec_minmax(table, write, buffer, length, ppos);
6261  
6262  	for (i = 0; i < MAX_NR_ZONES; i++) {
6263  		if (sysctl_lowmem_reserve_ratio[i] < 1)
6264  			sysctl_lowmem_reserve_ratio[i] = 0;
6265  	}
6266  
6267  	setup_per_zone_lowmem_reserve();
6268  	return 0;
6269  }
6270  
6271  /*
6272   * percpu_pagelist_high_fraction - changes the pcp->high for each zone on each
6273   * cpu. It is the fraction of total pages in each zone that a hot per cpu
6274   * pagelist can have before it gets flushed back to buddy allocator.
6275   */
percpu_pagelist_high_fraction_sysctl_handler(const struct ctl_table * table,int write,void * buffer,size_t * length,loff_t * ppos)6276  static int percpu_pagelist_high_fraction_sysctl_handler(const struct ctl_table *table,
6277  		int write, void *buffer, size_t *length, loff_t *ppos)
6278  {
6279  	struct zone *zone;
6280  	int old_percpu_pagelist_high_fraction;
6281  	int ret;
6282  
6283  	mutex_lock(&pcp_batch_high_lock);
6284  	old_percpu_pagelist_high_fraction = percpu_pagelist_high_fraction;
6285  
6286  	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
6287  	if (!write || ret < 0)
6288  		goto out;
6289  
6290  	/* Sanity checking to avoid pcp imbalance */
6291  	if (percpu_pagelist_high_fraction &&
6292  	    percpu_pagelist_high_fraction < MIN_PERCPU_PAGELIST_HIGH_FRACTION) {
6293  		percpu_pagelist_high_fraction = old_percpu_pagelist_high_fraction;
6294  		ret = -EINVAL;
6295  		goto out;
6296  	}
6297  
6298  	/* No change? */
6299  	if (percpu_pagelist_high_fraction == old_percpu_pagelist_high_fraction)
6300  		goto out;
6301  
6302  	for_each_populated_zone(zone)
6303  		zone_set_pageset_high_and_batch(zone, 0);
6304  out:
6305  	mutex_unlock(&pcp_batch_high_lock);
6306  	return ret;
6307  }
6308  
6309  static struct ctl_table page_alloc_sysctl_table[] = {
6310  	{
6311  		.procname	= "min_free_kbytes",
6312  		.data		= &min_free_kbytes,
6313  		.maxlen		= sizeof(min_free_kbytes),
6314  		.mode		= 0644,
6315  		.proc_handler	= min_free_kbytes_sysctl_handler,
6316  		.extra1		= SYSCTL_ZERO,
6317  	},
6318  	{
6319  		.procname	= "watermark_boost_factor",
6320  		.data		= &watermark_boost_factor,
6321  		.maxlen		= sizeof(watermark_boost_factor),
6322  		.mode		= 0644,
6323  		.proc_handler	= proc_dointvec_minmax,
6324  		.extra1		= SYSCTL_ZERO,
6325  	},
6326  	{
6327  		.procname	= "watermark_scale_factor",
6328  		.data		= &watermark_scale_factor,
6329  		.maxlen		= sizeof(watermark_scale_factor),
6330  		.mode		= 0644,
6331  		.proc_handler	= watermark_scale_factor_sysctl_handler,
6332  		.extra1		= SYSCTL_ONE,
6333  		.extra2		= SYSCTL_THREE_THOUSAND,
6334  	},
6335  	{
6336  		.procname	= "percpu_pagelist_high_fraction",
6337  		.data		= &percpu_pagelist_high_fraction,
6338  		.maxlen		= sizeof(percpu_pagelist_high_fraction),
6339  		.mode		= 0644,
6340  		.proc_handler	= percpu_pagelist_high_fraction_sysctl_handler,
6341  		.extra1		= SYSCTL_ZERO,
6342  	},
6343  	{
6344  		.procname	= "lowmem_reserve_ratio",
6345  		.data		= &sysctl_lowmem_reserve_ratio,
6346  		.maxlen		= sizeof(sysctl_lowmem_reserve_ratio),
6347  		.mode		= 0644,
6348  		.proc_handler	= lowmem_reserve_ratio_sysctl_handler,
6349  	},
6350  #ifdef CONFIG_NUMA
6351  	{
6352  		.procname	= "numa_zonelist_order",
6353  		.data		= &numa_zonelist_order,
6354  		.maxlen		= NUMA_ZONELIST_ORDER_LEN,
6355  		.mode		= 0644,
6356  		.proc_handler	= numa_zonelist_order_handler,
6357  	},
6358  	{
6359  		.procname	= "min_unmapped_ratio",
6360  		.data		= &sysctl_min_unmapped_ratio,
6361  		.maxlen		= sizeof(sysctl_min_unmapped_ratio),
6362  		.mode		= 0644,
6363  		.proc_handler	= sysctl_min_unmapped_ratio_sysctl_handler,
6364  		.extra1		= SYSCTL_ZERO,
6365  		.extra2		= SYSCTL_ONE_HUNDRED,
6366  	},
6367  	{
6368  		.procname	= "min_slab_ratio",
6369  		.data		= &sysctl_min_slab_ratio,
6370  		.maxlen		= sizeof(sysctl_min_slab_ratio),
6371  		.mode		= 0644,
6372  		.proc_handler	= sysctl_min_slab_ratio_sysctl_handler,
6373  		.extra1		= SYSCTL_ZERO,
6374  		.extra2		= SYSCTL_ONE_HUNDRED,
6375  	},
6376  #endif
6377  };
6378  
page_alloc_sysctl_init(void)6379  void __init page_alloc_sysctl_init(void)
6380  {
6381  	register_sysctl_init("vm", page_alloc_sysctl_table);
6382  }
6383  
6384  #ifdef CONFIG_CONTIG_ALLOC
6385  /* Usage: See admin-guide/dynamic-debug-howto.rst */
alloc_contig_dump_pages(struct list_head * page_list)6386  static void alloc_contig_dump_pages(struct list_head *page_list)
6387  {
6388  	DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, "migrate failure");
6389  
6390  	if (DYNAMIC_DEBUG_BRANCH(descriptor)) {
6391  		struct page *page;
6392  
6393  		dump_stack();
6394  		list_for_each_entry(page, page_list, lru)
6395  			dump_page(page, "migration failure");
6396  	}
6397  }
6398  
6399  /*
6400   * [start, end) must belong to a single zone.
6401   * @migratetype: using migratetype to filter the type of migration in
6402   *		trace_mm_alloc_contig_migrate_range_info.
6403   */
__alloc_contig_migrate_range(struct compact_control * cc,unsigned long start,unsigned long end,int migratetype)6404  int __alloc_contig_migrate_range(struct compact_control *cc,
6405  					unsigned long start, unsigned long end,
6406  					int migratetype)
6407  {
6408  	/* This function is based on compact_zone() from compaction.c. */
6409  	unsigned int nr_reclaimed;
6410  	unsigned long pfn = start;
6411  	unsigned int tries = 0;
6412  	int ret = 0;
6413  	struct migration_target_control mtc = {
6414  		.nid = zone_to_nid(cc->zone),
6415  		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
6416  		.reason = MR_CONTIG_RANGE,
6417  	};
6418  	struct page *page;
6419  	unsigned long total_mapped = 0;
6420  	unsigned long total_migrated = 0;
6421  	unsigned long total_reclaimed = 0;
6422  
6423  	lru_cache_disable();
6424  
6425  	while (pfn < end || !list_empty(&cc->migratepages)) {
6426  		if (fatal_signal_pending(current)) {
6427  			ret = -EINTR;
6428  			break;
6429  		}
6430  
6431  		if (list_empty(&cc->migratepages)) {
6432  			cc->nr_migratepages = 0;
6433  			ret = isolate_migratepages_range(cc, pfn, end);
6434  			if (ret && ret != -EAGAIN)
6435  				break;
6436  			pfn = cc->migrate_pfn;
6437  			tries = 0;
6438  		} else if (++tries == 5) {
6439  			ret = -EBUSY;
6440  			break;
6441  		}
6442  
6443  		nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
6444  							&cc->migratepages);
6445  		cc->nr_migratepages -= nr_reclaimed;
6446  
6447  		if (trace_mm_alloc_contig_migrate_range_info_enabled()) {
6448  			total_reclaimed += nr_reclaimed;
6449  			list_for_each_entry(page, &cc->migratepages, lru) {
6450  				struct folio *folio = page_folio(page);
6451  
6452  				total_mapped += folio_mapped(folio) *
6453  						folio_nr_pages(folio);
6454  			}
6455  		}
6456  
6457  		ret = migrate_pages(&cc->migratepages, alloc_migration_target,
6458  			NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE, NULL);
6459  
6460  		if (trace_mm_alloc_contig_migrate_range_info_enabled() && !ret)
6461  			total_migrated += cc->nr_migratepages;
6462  
6463  		/*
6464  		 * On -ENOMEM, migrate_pages() bails out right away. It is pointless
6465  		 * to retry again over this error, so do the same here.
6466  		 */
6467  		if (ret == -ENOMEM)
6468  			break;
6469  	}
6470  
6471  	lru_cache_enable();
6472  	if (ret < 0) {
6473  		if (!(cc->gfp_mask & __GFP_NOWARN) && ret == -EBUSY)
6474  			alloc_contig_dump_pages(&cc->migratepages);
6475  		putback_movable_pages(&cc->migratepages);
6476  	}
6477  
6478  	trace_mm_alloc_contig_migrate_range_info(start, end, migratetype,
6479  						 total_migrated,
6480  						 total_reclaimed,
6481  						 total_mapped);
6482  	return (ret < 0) ? ret : 0;
6483  }
6484  
split_free_pages(struct list_head * list)6485  static void split_free_pages(struct list_head *list)
6486  {
6487  	int order;
6488  
6489  	for (order = 0; order < NR_PAGE_ORDERS; order++) {
6490  		struct page *page, *next;
6491  		int nr_pages = 1 << order;
6492  
6493  		list_for_each_entry_safe(page, next, &list[order], lru) {
6494  			int i;
6495  
6496  			post_alloc_hook(page, order, __GFP_MOVABLE);
6497  			if (!order)
6498  				continue;
6499  
6500  			split_page(page, order);
6501  
6502  			/* Add all subpages to the order-0 head, in sequence. */
6503  			list_del(&page->lru);
6504  			for (i = 0; i < nr_pages; i++)
6505  				list_add_tail(&page[i].lru, &list[0]);
6506  		}
6507  	}
6508  }
6509  
6510  /**
6511   * alloc_contig_range() -- tries to allocate given range of pages
6512   * @start:	start PFN to allocate
6513   * @end:	one-past-the-last PFN to allocate
6514   * @migratetype:	migratetype of the underlying pageblocks (either
6515   *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
6516   *			in range must have the same migratetype and it must
6517   *			be either of the two.
6518   * @gfp_mask:	GFP mask to use during compaction
6519   *
6520   * The PFN range does not have to be pageblock aligned. The PFN range must
6521   * belong to a single zone.
6522   *
6523   * The first thing this routine does is attempt to MIGRATE_ISOLATE all
6524   * pageblocks in the range.  Once isolated, the pageblocks should not
6525   * be modified by others.
6526   *
6527   * Return: zero on success or negative error code.  On success all
6528   * pages which PFN is in [start, end) are allocated for the caller and
6529   * need to be freed with free_contig_range().
6530   */
alloc_contig_range_noprof(unsigned long start,unsigned long end,unsigned migratetype,gfp_t gfp_mask)6531  int alloc_contig_range_noprof(unsigned long start, unsigned long end,
6532  		       unsigned migratetype, gfp_t gfp_mask)
6533  {
6534  	unsigned long outer_start, outer_end;
6535  	int ret = 0;
6536  
6537  	struct compact_control cc = {
6538  		.nr_migratepages = 0,
6539  		.order = -1,
6540  		.zone = page_zone(pfn_to_page(start)),
6541  		.mode = MIGRATE_SYNC,
6542  		.ignore_skip_hint = true,
6543  		.no_set_skip_hint = true,
6544  		.gfp_mask = current_gfp_context(gfp_mask),
6545  		.alloc_contig = true,
6546  	};
6547  	INIT_LIST_HEAD(&cc.migratepages);
6548  
6549  	/*
6550  	 * What we do here is we mark all pageblocks in range as
6551  	 * MIGRATE_ISOLATE.  Because pageblock and max order pages may
6552  	 * have different sizes, and due to the way page allocator
6553  	 * work, start_isolate_page_range() has special handlings for this.
6554  	 *
6555  	 * Once the pageblocks are marked as MIGRATE_ISOLATE, we
6556  	 * migrate the pages from an unaligned range (ie. pages that
6557  	 * we are interested in). This will put all the pages in
6558  	 * range back to page allocator as MIGRATE_ISOLATE.
6559  	 *
6560  	 * When this is done, we take the pages in range from page
6561  	 * allocator removing them from the buddy system.  This way
6562  	 * page allocator will never consider using them.
6563  	 *
6564  	 * This lets us mark the pageblocks back as
6565  	 * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
6566  	 * aligned range but not in the unaligned, original range are
6567  	 * put back to page allocator so that buddy can use them.
6568  	 */
6569  
6570  	ret = start_isolate_page_range(start, end, migratetype, 0, gfp_mask);
6571  	if (ret)
6572  		goto done;
6573  
6574  	drain_all_pages(cc.zone);
6575  
6576  	/*
6577  	 * In case of -EBUSY, we'd like to know which page causes problem.
6578  	 * So, just fall through. test_pages_isolated() has a tracepoint
6579  	 * which will report the busy page.
6580  	 *
6581  	 * It is possible that busy pages could become available before
6582  	 * the call to test_pages_isolated, and the range will actually be
6583  	 * allocated.  So, if we fall through be sure to clear ret so that
6584  	 * -EBUSY is not accidentally used or returned to caller.
6585  	 */
6586  	ret = __alloc_contig_migrate_range(&cc, start, end, migratetype);
6587  	if (ret && ret != -EBUSY)
6588  		goto done;
6589  	ret = 0;
6590  
6591  	/*
6592  	 * Pages from [start, end) are within a pageblock_nr_pages
6593  	 * aligned blocks that are marked as MIGRATE_ISOLATE.  What's
6594  	 * more, all pages in [start, end) are free in page allocator.
6595  	 * What we are going to do is to allocate all pages from
6596  	 * [start, end) (that is remove them from page allocator).
6597  	 *
6598  	 * The only problem is that pages at the beginning and at the
6599  	 * end of interesting range may be not aligned with pages that
6600  	 * page allocator holds, ie. they can be part of higher order
6601  	 * pages.  Because of this, we reserve the bigger range and
6602  	 * once this is done free the pages we are not interested in.
6603  	 *
6604  	 * We don't have to hold zone->lock here because the pages are
6605  	 * isolated thus they won't get removed from buddy.
6606  	 */
6607  	outer_start = find_large_buddy(start);
6608  
6609  	/* Make sure the range is really isolated. */
6610  	if (test_pages_isolated(outer_start, end, 0)) {
6611  		ret = -EBUSY;
6612  		goto done;
6613  	}
6614  
6615  	/* Grab isolated pages from freelists. */
6616  	outer_end = isolate_freepages_range(&cc, outer_start, end);
6617  	if (!outer_end) {
6618  		ret = -EBUSY;
6619  		goto done;
6620  	}
6621  
6622  	if (!(gfp_mask & __GFP_COMP)) {
6623  		split_free_pages(cc.freepages);
6624  
6625  		/* Free head and tail (if any) */
6626  		if (start != outer_start)
6627  			free_contig_range(outer_start, start - outer_start);
6628  		if (end != outer_end)
6629  			free_contig_range(end, outer_end - end);
6630  	} else if (start == outer_start && end == outer_end && is_power_of_2(end - start)) {
6631  		struct page *head = pfn_to_page(start);
6632  		int order = ilog2(end - start);
6633  
6634  		check_new_pages(head, order);
6635  		prep_new_page(head, order, gfp_mask, 0);
6636  	} else {
6637  		ret = -EINVAL;
6638  		WARN(true, "PFN range: requested [%lu, %lu), allocated [%lu, %lu)\n",
6639  		     start, end, outer_start, outer_end);
6640  	}
6641  done:
6642  	undo_isolate_page_range(start, end, migratetype);
6643  	return ret;
6644  }
6645  EXPORT_SYMBOL(alloc_contig_range_noprof);
6646  
__alloc_contig_pages(unsigned long start_pfn,unsigned long nr_pages,gfp_t gfp_mask)6647  static int __alloc_contig_pages(unsigned long start_pfn,
6648  				unsigned long nr_pages, gfp_t gfp_mask)
6649  {
6650  	unsigned long end_pfn = start_pfn + nr_pages;
6651  
6652  	return alloc_contig_range_noprof(start_pfn, end_pfn, MIGRATE_MOVABLE,
6653  				   gfp_mask);
6654  }
6655  
pfn_range_valid_contig(struct zone * z,unsigned long start_pfn,unsigned long nr_pages)6656  static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
6657  				   unsigned long nr_pages)
6658  {
6659  	unsigned long i, end_pfn = start_pfn + nr_pages;
6660  	struct page *page;
6661  
6662  	for (i = start_pfn; i < end_pfn; i++) {
6663  		page = pfn_to_online_page(i);
6664  		if (!page)
6665  			return false;
6666  
6667  		if (page_zone(page) != z)
6668  			return false;
6669  
6670  		if (PageReserved(page))
6671  			return false;
6672  
6673  		if (PageHuge(page))
6674  			return false;
6675  	}
6676  	return true;
6677  }
6678  
zone_spans_last_pfn(const struct zone * zone,unsigned long start_pfn,unsigned long nr_pages)6679  static bool zone_spans_last_pfn(const struct zone *zone,
6680  				unsigned long start_pfn, unsigned long nr_pages)
6681  {
6682  	unsigned long last_pfn = start_pfn + nr_pages - 1;
6683  
6684  	return zone_spans_pfn(zone, last_pfn);
6685  }
6686  
6687  /**
6688   * alloc_contig_pages() -- tries to find and allocate contiguous range of pages
6689   * @nr_pages:	Number of contiguous pages to allocate
6690   * @gfp_mask:	GFP mask to limit search and used during compaction
6691   * @nid:	Target node
6692   * @nodemask:	Mask for other possible nodes
6693   *
6694   * This routine is a wrapper around alloc_contig_range(). It scans over zones
6695   * on an applicable zonelist to find a contiguous pfn range which can then be
6696   * tried for allocation with alloc_contig_range(). This routine is intended
6697   * for allocation requests which can not be fulfilled with the buddy allocator.
6698   *
6699   * The allocated memory is always aligned to a page boundary. If nr_pages is a
6700   * power of two, then allocated range is also guaranteed to be aligned to same
6701   * nr_pages (e.g. 1GB request would be aligned to 1GB).
6702   *
6703   * Allocated pages can be freed with free_contig_range() or by manually calling
6704   * __free_page() on each allocated page.
6705   *
6706   * Return: pointer to contiguous pages on success, or NULL if not successful.
6707   */
alloc_contig_pages_noprof(unsigned long nr_pages,gfp_t gfp_mask,int nid,nodemask_t * nodemask)6708  struct page *alloc_contig_pages_noprof(unsigned long nr_pages, gfp_t gfp_mask,
6709  				 int nid, nodemask_t *nodemask)
6710  {
6711  	unsigned long ret, pfn, flags;
6712  	struct zonelist *zonelist;
6713  	struct zone *zone;
6714  	struct zoneref *z;
6715  
6716  	zonelist = node_zonelist(nid, gfp_mask);
6717  	for_each_zone_zonelist_nodemask(zone, z, zonelist,
6718  					gfp_zone(gfp_mask), nodemask) {
6719  		spin_lock_irqsave(&zone->lock, flags);
6720  
6721  		pfn = ALIGN(zone->zone_start_pfn, nr_pages);
6722  		while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
6723  			if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
6724  				/*
6725  				 * We release the zone lock here because
6726  				 * alloc_contig_range() will also lock the zone
6727  				 * at some point. If there's an allocation
6728  				 * spinning on this lock, it may win the race
6729  				 * and cause alloc_contig_range() to fail...
6730  				 */
6731  				spin_unlock_irqrestore(&zone->lock, flags);
6732  				ret = __alloc_contig_pages(pfn, nr_pages,
6733  							gfp_mask);
6734  				if (!ret)
6735  					return pfn_to_page(pfn);
6736  				spin_lock_irqsave(&zone->lock, flags);
6737  			}
6738  			pfn += nr_pages;
6739  		}
6740  		spin_unlock_irqrestore(&zone->lock, flags);
6741  	}
6742  	return NULL;
6743  }
6744  #endif /* CONFIG_CONTIG_ALLOC */
6745  
free_contig_range(unsigned long pfn,unsigned long nr_pages)6746  void free_contig_range(unsigned long pfn, unsigned long nr_pages)
6747  {
6748  	unsigned long count = 0;
6749  	struct folio *folio = pfn_folio(pfn);
6750  
6751  	if (folio_test_large(folio)) {
6752  		int expected = folio_nr_pages(folio);
6753  
6754  		if (nr_pages == expected)
6755  			folio_put(folio);
6756  		else
6757  			WARN(true, "PFN %lu: nr_pages %lu != expected %d\n",
6758  			     pfn, nr_pages, expected);
6759  		return;
6760  	}
6761  
6762  	for (; nr_pages--; pfn++) {
6763  		struct page *page = pfn_to_page(pfn);
6764  
6765  		count += page_count(page) != 1;
6766  		__free_page(page);
6767  	}
6768  	WARN(count != 0, "%lu pages are still in use!\n", count);
6769  }
6770  EXPORT_SYMBOL(free_contig_range);
6771  
6772  /*
6773   * Effectively disable pcplists for the zone by setting the high limit to 0
6774   * and draining all cpus. A concurrent page freeing on another CPU that's about
6775   * to put the page on pcplist will either finish before the drain and the page
6776   * will be drained, or observe the new high limit and skip the pcplist.
6777   *
6778   * Must be paired with a call to zone_pcp_enable().
6779   */
zone_pcp_disable(struct zone * zone)6780  void zone_pcp_disable(struct zone *zone)
6781  {
6782  	mutex_lock(&pcp_batch_high_lock);
6783  	__zone_set_pageset_high_and_batch(zone, 0, 0, 1);
6784  	__drain_all_pages(zone, true);
6785  }
6786  
zone_pcp_enable(struct zone * zone)6787  void zone_pcp_enable(struct zone *zone)
6788  {
6789  	__zone_set_pageset_high_and_batch(zone, zone->pageset_high_min,
6790  		zone->pageset_high_max, zone->pageset_batch);
6791  	mutex_unlock(&pcp_batch_high_lock);
6792  }
6793  
zone_pcp_reset(struct zone * zone)6794  void zone_pcp_reset(struct zone *zone)
6795  {
6796  	int cpu;
6797  	struct per_cpu_zonestat *pzstats;
6798  
6799  	if (zone->per_cpu_pageset != &boot_pageset) {
6800  		for_each_online_cpu(cpu) {
6801  			pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
6802  			drain_zonestat(zone, pzstats);
6803  		}
6804  		free_percpu(zone->per_cpu_pageset);
6805  		zone->per_cpu_pageset = &boot_pageset;
6806  		if (zone->per_cpu_zonestats != &boot_zonestats) {
6807  			free_percpu(zone->per_cpu_zonestats);
6808  			zone->per_cpu_zonestats = &boot_zonestats;
6809  		}
6810  	}
6811  }
6812  
6813  #ifdef CONFIG_MEMORY_HOTREMOVE
6814  /*
6815   * All pages in the range must be in a single zone, must not contain holes,
6816   * must span full sections, and must be isolated before calling this function.
6817   *
6818   * Returns the number of managed (non-PageOffline()) pages in the range: the
6819   * number of pages for which memory offlining code must adjust managed page
6820   * counters using adjust_managed_page_count().
6821   */
__offline_isolated_pages(unsigned long start_pfn,unsigned long end_pfn)6822  unsigned long __offline_isolated_pages(unsigned long start_pfn,
6823  		unsigned long end_pfn)
6824  {
6825  	unsigned long already_offline = 0, flags;
6826  	unsigned long pfn = start_pfn;
6827  	struct page *page;
6828  	struct zone *zone;
6829  	unsigned int order;
6830  
6831  	offline_mem_sections(pfn, end_pfn);
6832  	zone = page_zone(pfn_to_page(pfn));
6833  	spin_lock_irqsave(&zone->lock, flags);
6834  	while (pfn < end_pfn) {
6835  		page = pfn_to_page(pfn);
6836  		/*
6837  		 * The HWPoisoned page may be not in buddy system, and
6838  		 * page_count() is not 0.
6839  		 */
6840  		if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
6841  			pfn++;
6842  			continue;
6843  		}
6844  		/*
6845  		 * At this point all remaining PageOffline() pages have a
6846  		 * reference count of 0 and can simply be skipped.
6847  		 */
6848  		if (PageOffline(page)) {
6849  			BUG_ON(page_count(page));
6850  			BUG_ON(PageBuddy(page));
6851  			already_offline++;
6852  			pfn++;
6853  			continue;
6854  		}
6855  
6856  		BUG_ON(page_count(page));
6857  		BUG_ON(!PageBuddy(page));
6858  		VM_WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE);
6859  		order = buddy_order(page);
6860  		del_page_from_free_list(page, zone, order, MIGRATE_ISOLATE);
6861  		pfn += (1 << order);
6862  	}
6863  	spin_unlock_irqrestore(&zone->lock, flags);
6864  
6865  	return end_pfn - start_pfn - already_offline;
6866  }
6867  #endif
6868  
6869  /*
6870   * This function returns a stable result only if called under zone lock.
6871   */
is_free_buddy_page(const struct page * page)6872  bool is_free_buddy_page(const struct page *page)
6873  {
6874  	unsigned long pfn = page_to_pfn(page);
6875  	unsigned int order;
6876  
6877  	for (order = 0; order < NR_PAGE_ORDERS; order++) {
6878  		const struct page *head = page - (pfn & ((1 << order) - 1));
6879  
6880  		if (PageBuddy(head) &&
6881  		    buddy_order_unsafe(head) >= order)
6882  			break;
6883  	}
6884  
6885  	return order <= MAX_PAGE_ORDER;
6886  }
6887  EXPORT_SYMBOL(is_free_buddy_page);
6888  
6889  #ifdef CONFIG_MEMORY_FAILURE
add_to_free_list(struct page * page,struct zone * zone,unsigned int order,int migratetype,bool tail)6890  static inline void add_to_free_list(struct page *page, struct zone *zone,
6891  				    unsigned int order, int migratetype,
6892  				    bool tail)
6893  {
6894  	__add_to_free_list(page, zone, order, migratetype, tail);
6895  	account_freepages(zone, 1 << order, migratetype);
6896  }
6897  
6898  /*
6899   * Break down a higher-order page in sub-pages, and keep our target out of
6900   * buddy allocator.
6901   */
break_down_buddy_pages(struct zone * zone,struct page * page,struct page * target,int low,int high,int migratetype)6902  static void break_down_buddy_pages(struct zone *zone, struct page *page,
6903  				   struct page *target, int low, int high,
6904  				   int migratetype)
6905  {
6906  	unsigned long size = 1 << high;
6907  	struct page *current_buddy;
6908  
6909  	while (high > low) {
6910  		high--;
6911  		size >>= 1;
6912  
6913  		if (target >= &page[size]) {
6914  			current_buddy = page;
6915  			page = page + size;
6916  		} else {
6917  			current_buddy = page + size;
6918  		}
6919  
6920  		if (set_page_guard(zone, current_buddy, high))
6921  			continue;
6922  
6923  		add_to_free_list(current_buddy, zone, high, migratetype, false);
6924  		set_buddy_order(current_buddy, high);
6925  	}
6926  }
6927  
6928  /*
6929   * Take a page that will be marked as poisoned off the buddy allocator.
6930   */
take_page_off_buddy(struct page * page)6931  bool take_page_off_buddy(struct page *page)
6932  {
6933  	struct zone *zone = page_zone(page);
6934  	unsigned long pfn = page_to_pfn(page);
6935  	unsigned long flags;
6936  	unsigned int order;
6937  	bool ret = false;
6938  
6939  	spin_lock_irqsave(&zone->lock, flags);
6940  	for (order = 0; order < NR_PAGE_ORDERS; order++) {
6941  		struct page *page_head = page - (pfn & ((1 << order) - 1));
6942  		int page_order = buddy_order(page_head);
6943  
6944  		if (PageBuddy(page_head) && page_order >= order) {
6945  			unsigned long pfn_head = page_to_pfn(page_head);
6946  			int migratetype = get_pfnblock_migratetype(page_head,
6947  								   pfn_head);
6948  
6949  			del_page_from_free_list(page_head, zone, page_order,
6950  						migratetype);
6951  			break_down_buddy_pages(zone, page_head, page, 0,
6952  						page_order, migratetype);
6953  			SetPageHWPoisonTakenOff(page);
6954  			ret = true;
6955  			break;
6956  		}
6957  		if (page_count(page_head) > 0)
6958  			break;
6959  	}
6960  	spin_unlock_irqrestore(&zone->lock, flags);
6961  	return ret;
6962  }
6963  
6964  /*
6965   * Cancel takeoff done by take_page_off_buddy().
6966   */
put_page_back_buddy(struct page * page)6967  bool put_page_back_buddy(struct page *page)
6968  {
6969  	struct zone *zone = page_zone(page);
6970  	unsigned long flags;
6971  	bool ret = false;
6972  
6973  	spin_lock_irqsave(&zone->lock, flags);
6974  	if (put_page_testzero(page)) {
6975  		unsigned long pfn = page_to_pfn(page);
6976  		int migratetype = get_pfnblock_migratetype(page, pfn);
6977  
6978  		ClearPageHWPoisonTakenOff(page);
6979  		__free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE);
6980  		if (TestClearPageHWPoison(page)) {
6981  			ret = true;
6982  		}
6983  	}
6984  	spin_unlock_irqrestore(&zone->lock, flags);
6985  
6986  	return ret;
6987  }
6988  #endif
6989  
6990  #ifdef CONFIG_ZONE_DMA
has_managed_dma(void)6991  bool has_managed_dma(void)
6992  {
6993  	struct pglist_data *pgdat;
6994  
6995  	for_each_online_pgdat(pgdat) {
6996  		struct zone *zone = &pgdat->node_zones[ZONE_DMA];
6997  
6998  		if (managed_zone(zone))
6999  			return true;
7000  	}
7001  	return false;
7002  }
7003  #endif /* CONFIG_ZONE_DMA */
7004  
7005  #ifdef CONFIG_UNACCEPTED_MEMORY
7006  
7007  /* Counts number of zones with unaccepted pages. */
7008  static DEFINE_STATIC_KEY_FALSE(zones_with_unaccepted_pages);
7009  
7010  static bool lazy_accept = true;
7011  
accept_memory_parse(char * p)7012  static int __init accept_memory_parse(char *p)
7013  {
7014  	if (!strcmp(p, "lazy")) {
7015  		lazy_accept = true;
7016  		return 0;
7017  	} else if (!strcmp(p, "eager")) {
7018  		lazy_accept = false;
7019  		return 0;
7020  	} else {
7021  		return -EINVAL;
7022  	}
7023  }
7024  early_param("accept_memory", accept_memory_parse);
7025  
page_contains_unaccepted(struct page * page,unsigned int order)7026  static bool page_contains_unaccepted(struct page *page, unsigned int order)
7027  {
7028  	phys_addr_t start = page_to_phys(page);
7029  
7030  	return range_contains_unaccepted_memory(start, PAGE_SIZE << order);
7031  }
7032  
__accept_page(struct zone * zone,unsigned long * flags,struct page * page)7033  static void __accept_page(struct zone *zone, unsigned long *flags,
7034  			  struct page *page)
7035  {
7036  	bool last;
7037  
7038  	list_del(&page->lru);
7039  	last = list_empty(&zone->unaccepted_pages);
7040  
7041  	account_freepages(zone, -MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
7042  	__mod_zone_page_state(zone, NR_UNACCEPTED, -MAX_ORDER_NR_PAGES);
7043  	__ClearPageUnaccepted(page);
7044  	spin_unlock_irqrestore(&zone->lock, *flags);
7045  
7046  	accept_memory(page_to_phys(page), PAGE_SIZE << MAX_PAGE_ORDER);
7047  
7048  	__free_pages_ok(page, MAX_PAGE_ORDER, FPI_TO_TAIL);
7049  
7050  	if (last)
7051  		static_branch_dec(&zones_with_unaccepted_pages);
7052  }
7053  
accept_page(struct page * page)7054  void accept_page(struct page *page)
7055  {
7056  	struct zone *zone = page_zone(page);
7057  	unsigned long flags;
7058  
7059  	spin_lock_irqsave(&zone->lock, flags);
7060  	if (!PageUnaccepted(page)) {
7061  		spin_unlock_irqrestore(&zone->lock, flags);
7062  		return;
7063  	}
7064  
7065  	/* Unlocks zone->lock */
7066  	__accept_page(zone, &flags, page);
7067  }
7068  
try_to_accept_memory_one(struct zone * zone)7069  static bool try_to_accept_memory_one(struct zone *zone)
7070  {
7071  	unsigned long flags;
7072  	struct page *page;
7073  
7074  	spin_lock_irqsave(&zone->lock, flags);
7075  	page = list_first_entry_or_null(&zone->unaccepted_pages,
7076  					struct page, lru);
7077  	if (!page) {
7078  		spin_unlock_irqrestore(&zone->lock, flags);
7079  		return false;
7080  	}
7081  
7082  	/* Unlocks zone->lock */
7083  	__accept_page(zone, &flags, page);
7084  
7085  	return true;
7086  }
7087  
has_unaccepted_memory(void)7088  static inline bool has_unaccepted_memory(void)
7089  {
7090  	return static_branch_unlikely(&zones_with_unaccepted_pages);
7091  }
7092  
cond_accept_memory(struct zone * zone,unsigned int order)7093  static bool cond_accept_memory(struct zone *zone, unsigned int order)
7094  {
7095  	long to_accept;
7096  	bool ret = false;
7097  
7098  	if (!has_unaccepted_memory())
7099  		return false;
7100  
7101  	if (list_empty(&zone->unaccepted_pages))
7102  		return false;
7103  
7104  	/* How much to accept to get to promo watermark? */
7105  	to_accept = promo_wmark_pages(zone) -
7106  		    (zone_page_state(zone, NR_FREE_PAGES) -
7107  		    __zone_watermark_unusable_free(zone, order, 0) -
7108  		    zone_page_state(zone, NR_UNACCEPTED));
7109  
7110  	while (to_accept > 0) {
7111  		if (!try_to_accept_memory_one(zone))
7112  			break;
7113  		ret = true;
7114  		to_accept -= MAX_ORDER_NR_PAGES;
7115  	}
7116  
7117  	return ret;
7118  }
7119  
__free_unaccepted(struct page * page)7120  static bool __free_unaccepted(struct page *page)
7121  {
7122  	struct zone *zone = page_zone(page);
7123  	unsigned long flags;
7124  	bool first = false;
7125  
7126  	if (!lazy_accept)
7127  		return false;
7128  
7129  	spin_lock_irqsave(&zone->lock, flags);
7130  	first = list_empty(&zone->unaccepted_pages);
7131  	list_add_tail(&page->lru, &zone->unaccepted_pages);
7132  	account_freepages(zone, MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
7133  	__mod_zone_page_state(zone, NR_UNACCEPTED, MAX_ORDER_NR_PAGES);
7134  	__SetPageUnaccepted(page);
7135  	spin_unlock_irqrestore(&zone->lock, flags);
7136  
7137  	if (first)
7138  		static_branch_inc(&zones_with_unaccepted_pages);
7139  
7140  	return true;
7141  }
7142  
7143  #else
7144  
page_contains_unaccepted(struct page * page,unsigned int order)7145  static bool page_contains_unaccepted(struct page *page, unsigned int order)
7146  {
7147  	return false;
7148  }
7149  
cond_accept_memory(struct zone * zone,unsigned int order)7150  static bool cond_accept_memory(struct zone *zone, unsigned int order)
7151  {
7152  	return false;
7153  }
7154  
__free_unaccepted(struct page * page)7155  static bool __free_unaccepted(struct page *page)
7156  {
7157  	BUILD_BUG();
7158  	return false;
7159  }
7160  
7161  #endif /* CONFIG_UNACCEPTED_MEMORY */
7162