1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/debugfs.h>
3 #include <linux/mm.h>
4 #include <linux/slab.h>
5 #include <linux/uaccess.h>
6 #include <linux/memblock.h>
7 #include <linux/stacktrace.h>
8 #include <linux/page_owner.h>
9 #include <linux/jump_label.h>
10 #include <linux/migrate.h>
11 #include <linux/stackdepot.h>
12 #include <linux/seq_file.h>
13 #include <linux/memcontrol.h>
14 #include <linux/sched/clock.h>
15 
16 #include "internal.h"
17 
18 /*
19  * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
20  * to use off stack temporal storage
21  */
22 #define PAGE_OWNER_STACK_DEPTH (16)
23 
24 struct page_owner {
25 	unsigned short order;
26 	short last_migrate_reason;
27 	gfp_t gfp_mask;
28 	depot_stack_handle_t handle;
29 	depot_stack_handle_t free_handle;
30 	u64 ts_nsec;
31 	u64 free_ts_nsec;
32 	char comm[TASK_COMM_LEN];
33 	pid_t pid;
34 	pid_t tgid;
35 	pid_t free_pid;
36 	pid_t free_tgid;
37 };
38 
39 struct stack {
40 	struct stack_record *stack_record;
41 	struct stack *next;
42 };
43 static struct stack dummy_stack;
44 static struct stack failure_stack;
45 static struct stack *stack_list;
46 static DEFINE_SPINLOCK(stack_list_lock);
47 
48 static bool page_owner_enabled __initdata;
49 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
50 
51 static depot_stack_handle_t dummy_handle;
52 static depot_stack_handle_t failure_handle;
53 static depot_stack_handle_t early_handle;
54 
55 static void init_early_allocated_pages(void);
56 
set_current_in_page_owner(void)57 static inline void set_current_in_page_owner(void)
58 {
59 	/*
60 	 * Avoid recursion.
61 	 *
62 	 * We might need to allocate more memory from page_owner code, so make
63 	 * sure to signal it in order to avoid recursion.
64 	 */
65 	current->in_page_owner = 1;
66 }
67 
unset_current_in_page_owner(void)68 static inline void unset_current_in_page_owner(void)
69 {
70 	current->in_page_owner = 0;
71 }
72 
early_page_owner_param(char * buf)73 static int __init early_page_owner_param(char *buf)
74 {
75 	int ret = kstrtobool(buf, &page_owner_enabled);
76 
77 	if (page_owner_enabled)
78 		stack_depot_request_early_init();
79 
80 	return ret;
81 }
82 early_param("page_owner", early_page_owner_param);
83 
need_page_owner(void)84 static __init bool need_page_owner(void)
85 {
86 	return page_owner_enabled;
87 }
88 
create_dummy_stack(void)89 static __always_inline depot_stack_handle_t create_dummy_stack(void)
90 {
91 	unsigned long entries[4];
92 	unsigned int nr_entries;
93 
94 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
95 	return stack_depot_save(entries, nr_entries, GFP_KERNEL);
96 }
97 
register_dummy_stack(void)98 static noinline void register_dummy_stack(void)
99 {
100 	dummy_handle = create_dummy_stack();
101 }
102 
register_failure_stack(void)103 static noinline void register_failure_stack(void)
104 {
105 	failure_handle = create_dummy_stack();
106 }
107 
register_early_stack(void)108 static noinline void register_early_stack(void)
109 {
110 	early_handle = create_dummy_stack();
111 }
112 
init_page_owner(void)113 static __init void init_page_owner(void)
114 {
115 	if (!page_owner_enabled)
116 		return;
117 
118 	register_dummy_stack();
119 	register_failure_stack();
120 	register_early_stack();
121 	init_early_allocated_pages();
122 	/* Initialize dummy and failure stacks and link them to stack_list */
123 	dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle);
124 	failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle);
125 	if (dummy_stack.stack_record)
126 		refcount_set(&dummy_stack.stack_record->count, 1);
127 	if (failure_stack.stack_record)
128 		refcount_set(&failure_stack.stack_record->count, 1);
129 	dummy_stack.next = &failure_stack;
130 	stack_list = &dummy_stack;
131 	static_branch_enable(&page_owner_inited);
132 }
133 
134 struct page_ext_operations page_owner_ops = {
135 	.size = sizeof(struct page_owner),
136 	.need = need_page_owner,
137 	.init = init_page_owner,
138 	.need_shared_flags = true,
139 };
140 
get_page_owner(struct page_ext * page_ext)141 static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
142 {
143 	return page_ext_data(page_ext, &page_owner_ops);
144 }
145 
save_stack(gfp_t flags)146 static noinline depot_stack_handle_t save_stack(gfp_t flags)
147 {
148 	unsigned long entries[PAGE_OWNER_STACK_DEPTH];
149 	depot_stack_handle_t handle;
150 	unsigned int nr_entries;
151 
152 	if (current->in_page_owner)
153 		return dummy_handle;
154 
155 	set_current_in_page_owner();
156 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
157 	handle = stack_depot_save(entries, nr_entries, flags);
158 	if (!handle)
159 		handle = failure_handle;
160 	unset_current_in_page_owner();
161 
162 	return handle;
163 }
164 
add_stack_record_to_list(struct stack_record * stack_record,gfp_t gfp_mask)165 static void add_stack_record_to_list(struct stack_record *stack_record,
166 				     gfp_t gfp_mask)
167 {
168 	unsigned long flags;
169 	struct stack *stack;
170 
171 	set_current_in_page_owner();
172 	stack = kmalloc(sizeof(*stack), gfp_nested_mask(gfp_mask));
173 	if (!stack) {
174 		unset_current_in_page_owner();
175 		return;
176 	}
177 	unset_current_in_page_owner();
178 
179 	stack->stack_record = stack_record;
180 	stack->next = NULL;
181 
182 	spin_lock_irqsave(&stack_list_lock, flags);
183 	stack->next = stack_list;
184 	/*
185 	 * This pairs with smp_load_acquire() from function
186 	 * stack_start(). This guarantees that stack_start()
187 	 * will see an updated stack_list before starting to
188 	 * traverse the list.
189 	 */
190 	smp_store_release(&stack_list, stack);
191 	spin_unlock_irqrestore(&stack_list_lock, flags);
192 }
193 
inc_stack_record_count(depot_stack_handle_t handle,gfp_t gfp_mask,int nr_base_pages)194 static void inc_stack_record_count(depot_stack_handle_t handle, gfp_t gfp_mask,
195 				   int nr_base_pages)
196 {
197 	struct stack_record *stack_record = __stack_depot_get_stack_record(handle);
198 
199 	if (!stack_record)
200 		return;
201 
202 	/*
203 	 * New stack_record's that do not use STACK_DEPOT_FLAG_GET start
204 	 * with REFCOUNT_SATURATED to catch spurious increments of their
205 	 * refcount.
206 	 * Since we do not use STACK_DEPOT_FLAG_GET API, let us
207 	 * set a refcount of 1 ourselves.
208 	 */
209 	if (refcount_read(&stack_record->count) == REFCOUNT_SATURATED) {
210 		int old = REFCOUNT_SATURATED;
211 
212 		if (atomic_try_cmpxchg_relaxed(&stack_record->count.refs, &old, 1))
213 			/* Add the new stack_record to our list */
214 			add_stack_record_to_list(stack_record, gfp_mask);
215 	}
216 	refcount_add(nr_base_pages, &stack_record->count);
217 }
218 
dec_stack_record_count(depot_stack_handle_t handle,int nr_base_pages)219 static void dec_stack_record_count(depot_stack_handle_t handle,
220 				   int nr_base_pages)
221 {
222 	struct stack_record *stack_record = __stack_depot_get_stack_record(handle);
223 
224 	if (!stack_record)
225 		return;
226 
227 	if (refcount_sub_and_test(nr_base_pages, &stack_record->count))
228 		pr_warn("%s: refcount went to 0 for %u handle\n", __func__,
229 			handle);
230 }
231 
__update_page_owner_handle(struct page_ext * page_ext,depot_stack_handle_t handle,unsigned short order,gfp_t gfp_mask,short last_migrate_reason,u64 ts_nsec,pid_t pid,pid_t tgid,char * comm)232 static inline void __update_page_owner_handle(struct page_ext *page_ext,
233 					      depot_stack_handle_t handle,
234 					      unsigned short order,
235 					      gfp_t gfp_mask,
236 					      short last_migrate_reason, u64 ts_nsec,
237 					      pid_t pid, pid_t tgid, char *comm)
238 {
239 	int i;
240 	struct page_owner *page_owner;
241 
242 	for (i = 0; i < (1 << order); i++) {
243 		page_owner = get_page_owner(page_ext);
244 		page_owner->handle = handle;
245 		page_owner->order = order;
246 		page_owner->gfp_mask = gfp_mask;
247 		page_owner->last_migrate_reason = last_migrate_reason;
248 		page_owner->pid = pid;
249 		page_owner->tgid = tgid;
250 		page_owner->ts_nsec = ts_nsec;
251 		strscpy(page_owner->comm, comm,
252 			sizeof(page_owner->comm));
253 		__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
254 		__set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
255 		page_ext = page_ext_next(page_ext);
256 	}
257 }
258 
__update_page_owner_free_handle(struct page_ext * page_ext,depot_stack_handle_t handle,unsigned short order,pid_t pid,pid_t tgid,u64 free_ts_nsec)259 static inline void __update_page_owner_free_handle(struct page_ext *page_ext,
260 						   depot_stack_handle_t handle,
261 						   unsigned short order,
262 						   pid_t pid, pid_t tgid,
263 						   u64 free_ts_nsec)
264 {
265 	int i;
266 	struct page_owner *page_owner;
267 
268 	for (i = 0; i < (1 << order); i++) {
269 		page_owner = get_page_owner(page_ext);
270 		/* Only __reset_page_owner() wants to clear the bit */
271 		if (handle) {
272 			__clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
273 			page_owner->free_handle = handle;
274 		}
275 		page_owner->free_ts_nsec = free_ts_nsec;
276 		page_owner->free_pid = current->pid;
277 		page_owner->free_tgid = current->tgid;
278 		page_ext = page_ext_next(page_ext);
279 	}
280 }
281 
__reset_page_owner(struct page * page,unsigned short order)282 void __reset_page_owner(struct page *page, unsigned short order)
283 {
284 	struct page_ext *page_ext;
285 	depot_stack_handle_t handle;
286 	depot_stack_handle_t alloc_handle;
287 	struct page_owner *page_owner;
288 	u64 free_ts_nsec = local_clock();
289 
290 	page_ext = page_ext_get(page);
291 	if (unlikely(!page_ext))
292 		return;
293 
294 	page_owner = get_page_owner(page_ext);
295 	alloc_handle = page_owner->handle;
296 
297 	handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
298 	__update_page_owner_free_handle(page_ext, handle, order, current->pid,
299 					current->tgid, free_ts_nsec);
300 	page_ext_put(page_ext);
301 
302 	if (alloc_handle != early_handle)
303 		/*
304 		 * early_handle is being set as a handle for all those
305 		 * early allocated pages. See init_pages_in_zone().
306 		 * Since their refcount is not being incremented because
307 		 * the machinery is not ready yet, we cannot decrement
308 		 * their refcount either.
309 		 */
310 		dec_stack_record_count(alloc_handle, 1 << order);
311 }
312 
__set_page_owner(struct page * page,unsigned short order,gfp_t gfp_mask)313 noinline void __set_page_owner(struct page *page, unsigned short order,
314 					gfp_t gfp_mask)
315 {
316 	struct page_ext *page_ext;
317 	u64 ts_nsec = local_clock();
318 	depot_stack_handle_t handle;
319 
320 	handle = save_stack(gfp_mask);
321 
322 	page_ext = page_ext_get(page);
323 	if (unlikely(!page_ext))
324 		return;
325 	__update_page_owner_handle(page_ext, handle, order, gfp_mask, -1,
326 				   ts_nsec, current->pid, current->tgid,
327 				   current->comm);
328 	page_ext_put(page_ext);
329 	inc_stack_record_count(handle, gfp_mask, 1 << order);
330 }
331 
__set_page_owner_migrate_reason(struct page * page,int reason)332 void __set_page_owner_migrate_reason(struct page *page, int reason)
333 {
334 	struct page_ext *page_ext = page_ext_get(page);
335 	struct page_owner *page_owner;
336 
337 	if (unlikely(!page_ext))
338 		return;
339 
340 	page_owner = get_page_owner(page_ext);
341 	page_owner->last_migrate_reason = reason;
342 	page_ext_put(page_ext);
343 }
344 
__split_page_owner(struct page * page,int old_order,int new_order)345 void __split_page_owner(struct page *page, int old_order, int new_order)
346 {
347 	int i;
348 	struct page_ext *page_ext = page_ext_get(page);
349 	struct page_owner *page_owner;
350 
351 	if (unlikely(!page_ext))
352 		return;
353 
354 	for (i = 0; i < (1 << old_order); i++) {
355 		page_owner = get_page_owner(page_ext);
356 		page_owner->order = new_order;
357 		page_ext = page_ext_next(page_ext);
358 	}
359 	page_ext_put(page_ext);
360 }
361 
__folio_copy_owner(struct folio * newfolio,struct folio * old)362 void __folio_copy_owner(struct folio *newfolio, struct folio *old)
363 {
364 	int i;
365 	struct page_ext *old_ext;
366 	struct page_ext *new_ext;
367 	struct page_owner *old_page_owner;
368 	struct page_owner *new_page_owner;
369 	depot_stack_handle_t migrate_handle;
370 
371 	old_ext = page_ext_get(&old->page);
372 	if (unlikely(!old_ext))
373 		return;
374 
375 	new_ext = page_ext_get(&newfolio->page);
376 	if (unlikely(!new_ext)) {
377 		page_ext_put(old_ext);
378 		return;
379 	}
380 
381 	old_page_owner = get_page_owner(old_ext);
382 	new_page_owner = get_page_owner(new_ext);
383 	migrate_handle = new_page_owner->handle;
384 	__update_page_owner_handle(new_ext, old_page_owner->handle,
385 				   old_page_owner->order, old_page_owner->gfp_mask,
386 				   old_page_owner->last_migrate_reason,
387 				   old_page_owner->ts_nsec, old_page_owner->pid,
388 				   old_page_owner->tgid, old_page_owner->comm);
389 	/*
390 	 * Do not proactively clear PAGE_EXT_OWNER{_ALLOCATED} bits as the folio
391 	 * will be freed after migration. Keep them until then as they may be
392 	 * useful.
393 	 */
394 	__update_page_owner_free_handle(new_ext, 0, old_page_owner->order,
395 					old_page_owner->free_pid,
396 					old_page_owner->free_tgid,
397 					old_page_owner->free_ts_nsec);
398 	/*
399 	 * We linked the original stack to the new folio, we need to do the same
400 	 * for the new one and the old folio otherwise there will be an imbalance
401 	 * when subtracting those pages from the stack.
402 	 */
403 	for (i = 0; i < (1 << new_page_owner->order); i++) {
404 		old_page_owner->handle = migrate_handle;
405 		old_ext = page_ext_next(old_ext);
406 		old_page_owner = get_page_owner(old_ext);
407 	}
408 
409 	page_ext_put(new_ext);
410 	page_ext_put(old_ext);
411 }
412 
pagetypeinfo_showmixedcount_print(struct seq_file * m,pg_data_t * pgdat,struct zone * zone)413 void pagetypeinfo_showmixedcount_print(struct seq_file *m,
414 				       pg_data_t *pgdat, struct zone *zone)
415 {
416 	struct page *page;
417 	struct page_ext *page_ext;
418 	struct page_owner *page_owner;
419 	unsigned long pfn, block_end_pfn;
420 	unsigned long end_pfn = zone_end_pfn(zone);
421 	unsigned long count[MIGRATE_TYPES] = { 0, };
422 	int pageblock_mt, page_mt;
423 	int i;
424 
425 	/* Scan block by block. First and last block may be incomplete */
426 	pfn = zone->zone_start_pfn;
427 
428 	/*
429 	 * Walk the zone in pageblock_nr_pages steps. If a page block spans
430 	 * a zone boundary, it will be double counted between zones. This does
431 	 * not matter as the mixed block count will still be correct
432 	 */
433 	for (; pfn < end_pfn; ) {
434 		page = pfn_to_online_page(pfn);
435 		if (!page) {
436 			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
437 			continue;
438 		}
439 
440 		block_end_pfn = pageblock_end_pfn(pfn);
441 		block_end_pfn = min(block_end_pfn, end_pfn);
442 
443 		pageblock_mt = get_pageblock_migratetype(page);
444 
445 		for (; pfn < block_end_pfn; pfn++) {
446 			/* The pageblock is online, no need to recheck. */
447 			page = pfn_to_page(pfn);
448 
449 			if (page_zone(page) != zone)
450 				continue;
451 
452 			if (PageBuddy(page)) {
453 				unsigned long freepage_order;
454 
455 				freepage_order = buddy_order_unsafe(page);
456 				if (freepage_order <= MAX_PAGE_ORDER)
457 					pfn += (1UL << freepage_order) - 1;
458 				continue;
459 			}
460 
461 			if (PageReserved(page))
462 				continue;
463 
464 			page_ext = page_ext_get(page);
465 			if (unlikely(!page_ext))
466 				continue;
467 
468 			if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
469 				goto ext_put_continue;
470 
471 			page_owner = get_page_owner(page_ext);
472 			page_mt = gfp_migratetype(page_owner->gfp_mask);
473 			if (pageblock_mt != page_mt) {
474 				if (is_migrate_cma(pageblock_mt))
475 					count[MIGRATE_MOVABLE]++;
476 				else
477 					count[pageblock_mt]++;
478 
479 				pfn = block_end_pfn;
480 				page_ext_put(page_ext);
481 				break;
482 			}
483 			pfn += (1UL << page_owner->order) - 1;
484 ext_put_continue:
485 			page_ext_put(page_ext);
486 		}
487 	}
488 
489 	/* Print counts */
490 	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
491 	for (i = 0; i < MIGRATE_TYPES; i++)
492 		seq_printf(m, "%12lu ", count[i]);
493 	seq_putc(m, '\n');
494 }
495 
496 /*
497  * Looking for memcg information and print it out
498  */
print_page_owner_memcg(char * kbuf,size_t count,int ret,struct page * page)499 static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
500 					 struct page *page)
501 {
502 #ifdef CONFIG_MEMCG
503 	unsigned long memcg_data;
504 	struct mem_cgroup *memcg;
505 	bool online;
506 	char name[80];
507 
508 	rcu_read_lock();
509 	memcg_data = READ_ONCE(page->memcg_data);
510 	if (!memcg_data)
511 		goto out_unlock;
512 
513 	if (memcg_data & MEMCG_DATA_OBJEXTS)
514 		ret += scnprintf(kbuf + ret, count - ret,
515 				"Slab cache page\n");
516 
517 	memcg = page_memcg_check(page);
518 	if (!memcg)
519 		goto out_unlock;
520 
521 	online = (memcg->css.flags & CSS_ONLINE);
522 	cgroup_name(memcg->css.cgroup, name, sizeof(name));
523 	ret += scnprintf(kbuf + ret, count - ret,
524 			"Charged %sto %smemcg %s\n",
525 			PageMemcgKmem(page) ? "(via objcg) " : "",
526 			online ? "" : "offline ",
527 			name);
528 out_unlock:
529 	rcu_read_unlock();
530 #endif /* CONFIG_MEMCG */
531 
532 	return ret;
533 }
534 
535 static ssize_t
print_page_owner(char __user * buf,size_t count,unsigned long pfn,struct page * page,struct page_owner * page_owner,depot_stack_handle_t handle)536 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
537 		struct page *page, struct page_owner *page_owner,
538 		depot_stack_handle_t handle)
539 {
540 	int ret, pageblock_mt, page_mt;
541 	char *kbuf;
542 
543 	count = min_t(size_t, count, PAGE_SIZE);
544 	kbuf = kmalloc(count, GFP_KERNEL);
545 	if (!kbuf)
546 		return -ENOMEM;
547 
548 	ret = scnprintf(kbuf, count,
549 			"Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns\n",
550 			page_owner->order, page_owner->gfp_mask,
551 			&page_owner->gfp_mask, page_owner->pid,
552 			page_owner->tgid, page_owner->comm,
553 			page_owner->ts_nsec);
554 
555 	/* Print information relevant to grouping pages by mobility */
556 	pageblock_mt = get_pageblock_migratetype(page);
557 	page_mt  = gfp_migratetype(page_owner->gfp_mask);
558 	ret += scnprintf(kbuf + ret, count - ret,
559 			"PFN 0x%lx type %s Block %lu type %s Flags %pGp\n",
560 			pfn,
561 			migratetype_names[page_mt],
562 			pfn >> pageblock_order,
563 			migratetype_names[pageblock_mt],
564 			&page->flags);
565 
566 	ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
567 	if (ret >= count)
568 		goto err;
569 
570 	if (page_owner->last_migrate_reason != -1) {
571 		ret += scnprintf(kbuf + ret, count - ret,
572 			"Page has been migrated, last migrate reason: %s\n",
573 			migrate_reason_names[page_owner->last_migrate_reason]);
574 	}
575 
576 	ret = print_page_owner_memcg(kbuf, count, ret, page);
577 
578 	ret += snprintf(kbuf + ret, count - ret, "\n");
579 	if (ret >= count)
580 		goto err;
581 
582 	if (copy_to_user(buf, kbuf, ret))
583 		ret = -EFAULT;
584 
585 	kfree(kbuf);
586 	return ret;
587 
588 err:
589 	kfree(kbuf);
590 	return -ENOMEM;
591 }
592 
__dump_page_owner(const struct page * page)593 void __dump_page_owner(const struct page *page)
594 {
595 	struct page_ext *page_ext = page_ext_get((void *)page);
596 	struct page_owner *page_owner;
597 	depot_stack_handle_t handle;
598 	gfp_t gfp_mask;
599 	int mt;
600 
601 	if (unlikely(!page_ext)) {
602 		pr_alert("There is not page extension available.\n");
603 		return;
604 	}
605 
606 	page_owner = get_page_owner(page_ext);
607 	gfp_mask = page_owner->gfp_mask;
608 	mt = gfp_migratetype(gfp_mask);
609 
610 	if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
611 		pr_alert("page_owner info is not present (never set?)\n");
612 		page_ext_put(page_ext);
613 		return;
614 	}
615 
616 	if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
617 		pr_alert("page_owner tracks the page as allocated\n");
618 	else
619 		pr_alert("page_owner tracks the page as freed\n");
620 
621 	pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu, free_ts %llu\n",
622 		 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
623 		 page_owner->pid, page_owner->tgid, page_owner->comm,
624 		 page_owner->ts_nsec, page_owner->free_ts_nsec);
625 
626 	handle = READ_ONCE(page_owner->handle);
627 	if (!handle)
628 		pr_alert("page_owner allocation stack trace missing\n");
629 	else
630 		stack_depot_print(handle);
631 
632 	handle = READ_ONCE(page_owner->free_handle);
633 	if (!handle) {
634 		pr_alert("page_owner free stack trace missing\n");
635 	} else {
636 		pr_alert("page last free pid %d tgid %d stack trace:\n",
637 			  page_owner->free_pid, page_owner->free_tgid);
638 		stack_depot_print(handle);
639 	}
640 
641 	if (page_owner->last_migrate_reason != -1)
642 		pr_alert("page has been migrated, last migrate reason: %s\n",
643 			migrate_reason_names[page_owner->last_migrate_reason]);
644 	page_ext_put(page_ext);
645 }
646 
647 static ssize_t
read_page_owner(struct file * file,char __user * buf,size_t count,loff_t * ppos)648 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
649 {
650 	unsigned long pfn;
651 	struct page *page;
652 	struct page_ext *page_ext;
653 	struct page_owner *page_owner;
654 	depot_stack_handle_t handle;
655 
656 	if (!static_branch_unlikely(&page_owner_inited))
657 		return -EINVAL;
658 
659 	page = NULL;
660 	if (*ppos == 0)
661 		pfn = min_low_pfn;
662 	else
663 		pfn = *ppos;
664 	/* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
665 	while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
666 		pfn++;
667 
668 	/* Find an allocated page */
669 	for (; pfn < max_pfn; pfn++) {
670 		/*
671 		 * This temporary page_owner is required so
672 		 * that we can avoid the context switches while holding
673 		 * the rcu lock and copying the page owner information to
674 		 * user through copy_to_user() or GFP_KERNEL allocations.
675 		 */
676 		struct page_owner page_owner_tmp;
677 
678 		/*
679 		 * If the new page is in a new MAX_ORDER_NR_PAGES area,
680 		 * validate the area as existing, skip it if not
681 		 */
682 		if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
683 			pfn += MAX_ORDER_NR_PAGES - 1;
684 			continue;
685 		}
686 
687 		page = pfn_to_page(pfn);
688 		if (PageBuddy(page)) {
689 			unsigned long freepage_order = buddy_order_unsafe(page);
690 
691 			if (freepage_order <= MAX_PAGE_ORDER)
692 				pfn += (1UL << freepage_order) - 1;
693 			continue;
694 		}
695 
696 		page_ext = page_ext_get(page);
697 		if (unlikely(!page_ext))
698 			continue;
699 
700 		/*
701 		 * Some pages could be missed by concurrent allocation or free,
702 		 * because we don't hold the zone lock.
703 		 */
704 		if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
705 			goto ext_put_continue;
706 
707 		/*
708 		 * Although we do have the info about past allocation of free
709 		 * pages, it's not relevant for current memory usage.
710 		 */
711 		if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
712 			goto ext_put_continue;
713 
714 		page_owner = get_page_owner(page_ext);
715 
716 		/*
717 		 * Don't print "tail" pages of high-order allocations as that
718 		 * would inflate the stats.
719 		 */
720 		if (!IS_ALIGNED(pfn, 1 << page_owner->order))
721 			goto ext_put_continue;
722 
723 		/*
724 		 * Access to page_ext->handle isn't synchronous so we should
725 		 * be careful to access it.
726 		 */
727 		handle = READ_ONCE(page_owner->handle);
728 		if (!handle)
729 			goto ext_put_continue;
730 
731 		/* Record the next PFN to read in the file offset */
732 		*ppos = pfn + 1;
733 
734 		page_owner_tmp = *page_owner;
735 		page_ext_put(page_ext);
736 		return print_page_owner(buf, count, pfn, page,
737 				&page_owner_tmp, handle);
738 ext_put_continue:
739 		page_ext_put(page_ext);
740 	}
741 
742 	return 0;
743 }
744 
lseek_page_owner(struct file * file,loff_t offset,int orig)745 static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
746 {
747 	switch (orig) {
748 	case SEEK_SET:
749 		file->f_pos = offset;
750 		break;
751 	case SEEK_CUR:
752 		file->f_pos += offset;
753 		break;
754 	default:
755 		return -EINVAL;
756 	}
757 	return file->f_pos;
758 }
759 
init_pages_in_zone(pg_data_t * pgdat,struct zone * zone)760 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
761 {
762 	unsigned long pfn = zone->zone_start_pfn;
763 	unsigned long end_pfn = zone_end_pfn(zone);
764 	unsigned long count = 0;
765 
766 	/*
767 	 * Walk the zone in pageblock_nr_pages steps. If a page block spans
768 	 * a zone boundary, it will be double counted between zones. This does
769 	 * not matter as the mixed block count will still be correct
770 	 */
771 	for (; pfn < end_pfn; ) {
772 		unsigned long block_end_pfn;
773 
774 		if (!pfn_valid(pfn)) {
775 			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
776 			continue;
777 		}
778 
779 		block_end_pfn = pageblock_end_pfn(pfn);
780 		block_end_pfn = min(block_end_pfn, end_pfn);
781 
782 		for (; pfn < block_end_pfn; pfn++) {
783 			struct page *page = pfn_to_page(pfn);
784 			struct page_ext *page_ext;
785 
786 			if (page_zone(page) != zone)
787 				continue;
788 
789 			/*
790 			 * To avoid having to grab zone->lock, be a little
791 			 * careful when reading buddy page order. The only
792 			 * danger is that we skip too much and potentially miss
793 			 * some early allocated pages, which is better than
794 			 * heavy lock contention.
795 			 */
796 			if (PageBuddy(page)) {
797 				unsigned long order = buddy_order_unsafe(page);
798 
799 				if (order > 0 && order <= MAX_PAGE_ORDER)
800 					pfn += (1UL << order) - 1;
801 				continue;
802 			}
803 
804 			if (PageReserved(page))
805 				continue;
806 
807 			page_ext = page_ext_get(page);
808 			if (unlikely(!page_ext))
809 				continue;
810 
811 			/* Maybe overlapping zone */
812 			if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
813 				goto ext_put_continue;
814 
815 			/* Found early allocated page */
816 			__update_page_owner_handle(page_ext, early_handle, 0, 0,
817 						   -1, local_clock(), current->pid,
818 						   current->tgid, current->comm);
819 			count++;
820 ext_put_continue:
821 			page_ext_put(page_ext);
822 		}
823 		cond_resched();
824 	}
825 
826 	pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
827 		pgdat->node_id, zone->name, count);
828 }
829 
init_zones_in_node(pg_data_t * pgdat)830 static void init_zones_in_node(pg_data_t *pgdat)
831 {
832 	struct zone *zone;
833 	struct zone *node_zones = pgdat->node_zones;
834 
835 	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
836 		if (!populated_zone(zone))
837 			continue;
838 
839 		init_pages_in_zone(pgdat, zone);
840 	}
841 }
842 
init_early_allocated_pages(void)843 static void init_early_allocated_pages(void)
844 {
845 	pg_data_t *pgdat;
846 
847 	for_each_online_pgdat(pgdat)
848 		init_zones_in_node(pgdat);
849 }
850 
851 static const struct file_operations proc_page_owner_operations = {
852 	.read		= read_page_owner,
853 	.llseek		= lseek_page_owner,
854 };
855 
stack_start(struct seq_file * m,loff_t * ppos)856 static void *stack_start(struct seq_file *m, loff_t *ppos)
857 {
858 	struct stack *stack;
859 
860 	if (*ppos == -1UL)
861 		return NULL;
862 
863 	if (!*ppos) {
864 		/*
865 		 * This pairs with smp_store_release() from function
866 		 * add_stack_record_to_list(), so we get a consistent
867 		 * value of stack_list.
868 		 */
869 		stack = smp_load_acquire(&stack_list);
870 		m->private = stack;
871 	} else {
872 		stack = m->private;
873 	}
874 
875 	return stack;
876 }
877 
stack_next(struct seq_file * m,void * v,loff_t * ppos)878 static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
879 {
880 	struct stack *stack = v;
881 
882 	stack = stack->next;
883 	*ppos = stack ? *ppos + 1 : -1UL;
884 	m->private = stack;
885 
886 	return stack;
887 }
888 
889 static unsigned long page_owner_pages_threshold;
890 
stack_print(struct seq_file * m,void * v)891 static int stack_print(struct seq_file *m, void *v)
892 {
893 	int i, nr_base_pages;
894 	struct stack *stack = v;
895 	unsigned long *entries;
896 	unsigned long nr_entries;
897 	struct stack_record *stack_record = stack->stack_record;
898 
899 	if (!stack->stack_record)
900 		return 0;
901 
902 	nr_entries = stack_record->size;
903 	entries = stack_record->entries;
904 	nr_base_pages = refcount_read(&stack_record->count) - 1;
905 
906 	if (nr_base_pages < 1 || nr_base_pages < page_owner_pages_threshold)
907 		return 0;
908 
909 	for (i = 0; i < nr_entries; i++)
910 		seq_printf(m, " %pS\n", (void *)entries[i]);
911 	seq_printf(m, "nr_base_pages: %d\n\n", nr_base_pages);
912 
913 	return 0;
914 }
915 
stack_stop(struct seq_file * m,void * v)916 static void stack_stop(struct seq_file *m, void *v)
917 {
918 }
919 
920 static const struct seq_operations page_owner_stack_op = {
921 	.start	= stack_start,
922 	.next	= stack_next,
923 	.stop	= stack_stop,
924 	.show	= stack_print
925 };
926 
page_owner_stack_open(struct inode * inode,struct file * file)927 static int page_owner_stack_open(struct inode *inode, struct file *file)
928 {
929 	return seq_open_private(file, &page_owner_stack_op, 0);
930 }
931 
932 static const struct file_operations page_owner_stack_operations = {
933 	.open		= page_owner_stack_open,
934 	.read		= seq_read,
935 	.llseek		= seq_lseek,
936 	.release	= seq_release,
937 };
938 
page_owner_threshold_get(void * data,u64 * val)939 static int page_owner_threshold_get(void *data, u64 *val)
940 {
941 	*val = READ_ONCE(page_owner_pages_threshold);
942 	return 0;
943 }
944 
page_owner_threshold_set(void * data,u64 val)945 static int page_owner_threshold_set(void *data, u64 val)
946 {
947 	WRITE_ONCE(page_owner_pages_threshold, val);
948 	return 0;
949 }
950 
951 DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
952 			&page_owner_threshold_set, "%llu");
953 
954 
pageowner_init(void)955 static int __init pageowner_init(void)
956 {
957 	struct dentry *dir;
958 
959 	if (!static_branch_unlikely(&page_owner_inited)) {
960 		pr_info("page_owner is disabled\n");
961 		return 0;
962 	}
963 
964 	debugfs_create_file("page_owner", 0400, NULL, NULL,
965 			    &proc_page_owner_operations);
966 	dir = debugfs_create_dir("page_owner_stacks", NULL);
967 	debugfs_create_file("show_stacks", 0400, dir, NULL,
968 			    &page_owner_stack_operations);
969 	debugfs_create_file("count_threshold", 0600, dir, NULL,
970 			    &proc_page_owner_threshold);
971 
972 	return 0;
973 }
974 late_initcall(pageowner_init)
975