1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MIGRATE_H
3 #define _LINUX_MIGRATE_H
4
5 #include <linux/mm.h>
6 #include <linux/mempolicy.h>
7 #include <linux/migrate_mode.h>
8 #include <linux/hugetlb.h>
9
10 typedef struct folio *new_folio_t(struct folio *folio, unsigned long private);
11 typedef void free_folio_t(struct folio *folio, unsigned long private);
12
13 struct migration_target_control;
14
15 /*
16 * Return values from addresss_space_operations.migratepage():
17 * - negative errno on page migration failure;
18 * - zero on page migration success;
19 */
20 #define MIGRATEPAGE_SUCCESS 0
21 #define MIGRATEPAGE_UNMAP 1
22
23 /**
24 * struct movable_operations - Driver page migration
25 * @isolate_page:
26 * The VM calls this function to prepare the page to be moved. The page
27 * is locked and the driver should not unlock it. The driver should
28 * return ``true`` if the page is movable and ``false`` if it is not
29 * currently movable. After this function returns, the VM uses the
30 * page->lru field, so the driver must preserve any information which
31 * is usually stored here.
32 *
33 * @migrate_page:
34 * After isolation, the VM calls this function with the isolated
35 * @src page. The driver should copy the contents of the
36 * @src page to the @dst page and set up the fields of @dst page.
37 * Both pages are locked.
38 * If page migration is successful, the driver should call
39 * __ClearPageMovable(@src) and return MIGRATEPAGE_SUCCESS.
40 * If the driver cannot migrate the page at the moment, it can return
41 * -EAGAIN. The VM interprets this as a temporary migration failure and
42 * will retry it later. Any other error value is a permanent migration
43 * failure and migration will not be retried.
44 * The driver shouldn't touch the @src->lru field while in the
45 * migrate_page() function. It may write to @dst->lru.
46 *
47 * @putback_page:
48 * If migration fails on the isolated page, the VM informs the driver
49 * that the page is no longer a candidate for migration by calling
50 * this function. The driver should put the isolated page back into
51 * its own data structure.
52 */
53 struct movable_operations {
54 bool (*isolate_page)(struct page *, isolate_mode_t);
55 int (*migrate_page)(struct page *dst, struct page *src,
56 enum migrate_mode);
57 void (*putback_page)(struct page *);
58 };
59
60 /* Defined in mm/debug.c: */
61 extern const char *migrate_reason_names[MR_TYPES];
62
63 #ifdef CONFIG_MIGRATION
64
65 void putback_movable_pages(struct list_head *l);
66 int migrate_folio(struct address_space *mapping, struct folio *dst,
67 struct folio *src, enum migrate_mode mode);
68 int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
69 unsigned long private, enum migrate_mode mode, int reason,
70 unsigned int *ret_succeeded);
71 struct folio *alloc_migration_target(struct folio *src, unsigned long private);
72 bool isolate_movable_page(struct page *page, isolate_mode_t mode);
73 bool isolate_folio_to_list(struct folio *folio, struct list_head *list);
74
75 int migrate_huge_page_move_mapping(struct address_space *mapping,
76 struct folio *dst, struct folio *src);
77 void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
78 __releases(ptl);
79 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
80 int folio_migrate_mapping(struct address_space *mapping,
81 struct folio *newfolio, struct folio *folio, int extra_count);
82
83 #else
84
putback_movable_pages(struct list_head * l)85 static inline void putback_movable_pages(struct list_head *l) {}
migrate_pages(struct list_head * l,new_folio_t new,free_folio_t free,unsigned long private,enum migrate_mode mode,int reason,unsigned int * ret_succeeded)86 static inline int migrate_pages(struct list_head *l, new_folio_t new,
87 free_folio_t free, unsigned long private,
88 enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
89 { return -ENOSYS; }
alloc_migration_target(struct folio * src,unsigned long private)90 static inline struct folio *alloc_migration_target(struct folio *src,
91 unsigned long private)
92 { return NULL; }
isolate_movable_page(struct page * page,isolate_mode_t mode)93 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
94 { return false; }
isolate_folio_to_list(struct folio * folio,struct list_head * list)95 static inline bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
96 { return false; }
97
migrate_huge_page_move_mapping(struct address_space * mapping,struct folio * dst,struct folio * src)98 static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
99 struct folio *dst, struct folio *src)
100 {
101 return -ENOSYS;
102 }
103
104 #endif /* CONFIG_MIGRATION */
105
106 #ifdef CONFIG_COMPACTION
107 bool PageMovable(struct page *page);
108 void __SetPageMovable(struct page *page, const struct movable_operations *ops);
109 void __ClearPageMovable(struct page *page);
110 #else
PageMovable(struct page * page)111 static inline bool PageMovable(struct page *page) { return false; }
__SetPageMovable(struct page * page,const struct movable_operations * ops)112 static inline void __SetPageMovable(struct page *page,
113 const struct movable_operations *ops)
114 {
115 }
__ClearPageMovable(struct page * page)116 static inline void __ClearPageMovable(struct page *page)
117 {
118 }
119 #endif
120
folio_test_movable(struct folio * folio)121 static inline bool folio_test_movable(struct folio *folio)
122 {
123 return PageMovable(&folio->page);
124 }
125
126 static inline
folio_movable_ops(struct folio * folio)127 const struct movable_operations *folio_movable_ops(struct folio *folio)
128 {
129 VM_BUG_ON(!__folio_test_movable(folio));
130
131 return (const struct movable_operations *)
132 ((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE);
133 }
134
135 static inline
page_movable_ops(struct page * page)136 const struct movable_operations *page_movable_ops(struct page *page)
137 {
138 VM_BUG_ON(!__PageMovable(page));
139
140 return (const struct movable_operations *)
141 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
142 }
143
144 #ifdef CONFIG_NUMA_BALANCING
145 int migrate_misplaced_folio_prepare(struct folio *folio,
146 struct vm_area_struct *vma, int node);
147 int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
148 int node);
149 #else
migrate_misplaced_folio_prepare(struct folio * folio,struct vm_area_struct * vma,int node)150 static inline int migrate_misplaced_folio_prepare(struct folio *folio,
151 struct vm_area_struct *vma, int node)
152 {
153 return -EAGAIN; /* can't migrate now */
154 }
migrate_misplaced_folio(struct folio * folio,struct vm_area_struct * vma,int node)155 static inline int migrate_misplaced_folio(struct folio *folio,
156 struct vm_area_struct *vma, int node)
157 {
158 return -EAGAIN; /* can't migrate now */
159 }
160 #endif /* CONFIG_NUMA_BALANCING */
161
162 #ifdef CONFIG_MIGRATION
163
164 /*
165 * Watch out for PAE architecture, which has an unsigned long, and might not
166 * have enough bits to store all physical address and flags. So far we have
167 * enough room for all our flags.
168 */
169 #define MIGRATE_PFN_VALID (1UL << 0)
170 #define MIGRATE_PFN_MIGRATE (1UL << 1)
171 #define MIGRATE_PFN_WRITE (1UL << 3)
172 #define MIGRATE_PFN_SHIFT 6
173
migrate_pfn_to_page(unsigned long mpfn)174 static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
175 {
176 if (!(mpfn & MIGRATE_PFN_VALID))
177 return NULL;
178 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
179 }
180
migrate_pfn(unsigned long pfn)181 static inline unsigned long migrate_pfn(unsigned long pfn)
182 {
183 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
184 }
185
186 enum migrate_vma_direction {
187 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
188 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
189 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
190 };
191
192 struct migrate_vma {
193 struct vm_area_struct *vma;
194 /*
195 * Both src and dst array must be big enough for
196 * (end - start) >> PAGE_SHIFT entries.
197 *
198 * The src array must not be modified by the caller after
199 * migrate_vma_setup(), and must not change the dst array after
200 * migrate_vma_pages() returns.
201 */
202 unsigned long *dst;
203 unsigned long *src;
204 unsigned long cpages;
205 unsigned long npages;
206 unsigned long start;
207 unsigned long end;
208
209 /*
210 * Set to the owner value also stored in page->pgmap->owner for
211 * migrating out of device private memory. The flags also need to
212 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
213 * The caller should always set this field when using mmu notifier
214 * callbacks to avoid device MMU invalidations for device private
215 * pages that are not being migrated.
216 */
217 void *pgmap_owner;
218 unsigned long flags;
219
220 /*
221 * Set to vmf->page if this is being called to migrate a page as part of
222 * a migrate_to_ram() callback.
223 */
224 struct page *fault_page;
225 };
226
227 int migrate_vma_setup(struct migrate_vma *args);
228 void migrate_vma_pages(struct migrate_vma *migrate);
229 void migrate_vma_finalize(struct migrate_vma *migrate);
230 int migrate_device_range(unsigned long *src_pfns, unsigned long start,
231 unsigned long npages);
232 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns,
233 unsigned long npages);
234 void migrate_device_finalize(unsigned long *src_pfns,
235 unsigned long *dst_pfns, unsigned long npages);
236
237 #endif /* CONFIG_MIGRATION */
238
239 #endif /* _LINUX_MIGRATE_H */
240