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_extra(struct address_space *mapping, struct folio *dst,
67 struct folio *src, enum migrate_mode mode, int extra_count);
68 int migrate_folio(struct address_space *mapping, struct folio *dst,
69 struct folio *src, enum migrate_mode mode);
70 int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
71 unsigned long private, enum migrate_mode mode, int reason,
72 unsigned int *ret_succeeded);
73 struct folio *alloc_migration_target(struct folio *src, unsigned long private);
74 bool isolate_movable_page(struct page *page, isolate_mode_t mode);
75
76 int migrate_huge_page_move_mapping(struct address_space *mapping,
77 struct folio *dst, struct folio *src);
78 void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
79 __releases(ptl);
80 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
81 void folio_migrate_copy(struct folio *newfolio, struct folio *folio);
82 int folio_migrate_mapping(struct address_space *mapping,
83 struct folio *newfolio, struct folio *folio, int extra_count);
84
85 #else
86
putback_movable_pages(struct list_head * l)87 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)88 static inline int migrate_pages(struct list_head *l, new_folio_t new,
89 free_folio_t free, unsigned long private,
90 enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
91 { return -ENOSYS; }
alloc_migration_target(struct folio * src,unsigned long private)92 static inline struct folio *alloc_migration_target(struct folio *src,
93 unsigned long private)
94 { return NULL; }
isolate_movable_page(struct page * page,isolate_mode_t mode)95 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
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_page(struct page *page, struct vm_area_struct *vma,
146 int node);
147 #else
migrate_misplaced_page(struct page * page,struct vm_area_struct * vma,int node)148 static inline int migrate_misplaced_page(struct page *page,
149 struct vm_area_struct *vma, int node)
150 {
151 return -EAGAIN; /* can't migrate now */
152 }
153 #endif /* CONFIG_NUMA_BALANCING */
154
155 #ifdef CONFIG_MIGRATION
156
157 /*
158 * Watch out for PAE architecture, which has an unsigned long, and might not
159 * have enough bits to store all physical address and flags. So far we have
160 * enough room for all our flags.
161 */
162 #define MIGRATE_PFN_VALID (1UL << 0)
163 #define MIGRATE_PFN_MIGRATE (1UL << 1)
164 #define MIGRATE_PFN_WRITE (1UL << 3)
165 #define MIGRATE_PFN_SHIFT 6
166
migrate_pfn_to_page(unsigned long mpfn)167 static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
168 {
169 if (!(mpfn & MIGRATE_PFN_VALID))
170 return NULL;
171 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
172 }
173
migrate_pfn(unsigned long pfn)174 static inline unsigned long migrate_pfn(unsigned long pfn)
175 {
176 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
177 }
178
179 enum migrate_vma_direction {
180 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
181 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
182 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
183 };
184
185 struct migrate_vma {
186 struct vm_area_struct *vma;
187 /*
188 * Both src and dst array must be big enough for
189 * (end - start) >> PAGE_SHIFT entries.
190 *
191 * The src array must not be modified by the caller after
192 * migrate_vma_setup(), and must not change the dst array after
193 * migrate_vma_pages() returns.
194 */
195 unsigned long *dst;
196 unsigned long *src;
197 unsigned long cpages;
198 unsigned long npages;
199 unsigned long start;
200 unsigned long end;
201
202 /*
203 * Set to the owner value also stored in page->pgmap->owner for
204 * migrating out of device private memory. The flags also need to
205 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
206 * The caller should always set this field when using mmu notifier
207 * callbacks to avoid device MMU invalidations for device private
208 * pages that are not being migrated.
209 */
210 void *pgmap_owner;
211 unsigned long flags;
212
213 /*
214 * Set to vmf->page if this is being called to migrate a page as part of
215 * a migrate_to_ram() callback.
216 */
217 struct page *fault_page;
218 };
219
220 int migrate_vma_setup(struct migrate_vma *args);
221 void migrate_vma_pages(struct migrate_vma *migrate);
222 void migrate_vma_finalize(struct migrate_vma *migrate);
223 int migrate_device_range(unsigned long *src_pfns, unsigned long start,
224 unsigned long npages);
225 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns,
226 unsigned long npages);
227 void migrate_device_finalize(unsigned long *src_pfns,
228 unsigned long *dst_pfns, unsigned long npages);
229
230 #endif /* CONFIG_MIGRATION */
231
232 #endif /* _LINUX_MIGRATE_H */
233