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