Line data Source code
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 : #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_page_t new, free_page_t free,
71 : unsigned long private, enum migrate_mode mode, int reason,
72 : unsigned int *ret_succeeded);
73 : struct page *alloc_migration_target(struct page *page, 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, pte_t *ptep,
79 : spinlock_t *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 :
87 : static inline void putback_movable_pages(struct list_head *l) {}
88 : static inline int migrate_pages(struct list_head *l, new_page_t new,
89 : free_page_t free, unsigned long private, enum migrate_mode mode,
90 : int reason, unsigned int *ret_succeeded)
91 : { return -ENOSYS; }
92 : static inline struct page *alloc_migration_target(struct page *page,
93 : unsigned long private)
94 : { return NULL; }
95 : static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
96 : { return false; }
97 :
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
111 : static inline bool PageMovable(struct page *page) { return false; }
112 : static inline void __SetPageMovable(struct page *page,
113 : const struct movable_operations *ops)
114 : {
115 : }
116 : static inline void __ClearPageMovable(struct page *page)
117 : {
118 : }
119 : #endif
120 :
121 : static inline bool folio_test_movable(struct folio *folio)
122 : {
123 0 : return PageMovable(&folio->page);
124 : }
125 :
126 : static inline
127 : const struct movable_operations *folio_movable_ops(struct folio *folio)
128 : {
129 : VM_BUG_ON(!__folio_test_movable(folio));
130 :
131 0 : return (const struct movable_operations *)
132 0 : ((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE);
133 : }
134 :
135 : static inline
136 : const struct movable_operations *page_movable_ops(struct page *page)
137 : {
138 : VM_BUG_ON(!__PageMovable(page));
139 :
140 0 : return (const struct movable_operations *)
141 0 : ((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
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 :
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 :
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 */
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