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
74 int migrate_huge_page_move_mapping(struct address_space *mapping,
75 struct folio *dst, struct folio *src);
76 void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
77 __releases(ptl);
78 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
79 int folio_migrate_mapping(struct address_space *mapping,
80 struct folio *newfolio, struct folio *folio, int extra_count);
81
82 #else
83
84 static inline void putback_movable_pages(struct list_head *l) {}
85 static inline int migrate_pages(struct list_head *l, new_folio_t new,
86 free_folio_t free, unsigned long private,
87 enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
88 { return -ENOSYS; }
89 static inline struct folio *alloc_migration_target(struct folio *src,
90 unsigned long private)
91 { return NULL; }
92 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
93 { return false; }
94
95 static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
96 struct folio *dst, struct folio *src)
97 {
98 return -ENOSYS;
99 }
100
101 #endif /* CONFIG_MIGRATION */
102
103 #ifdef CONFIG_COMPACTION
104 bool PageMovable(struct page *page);
105 void __SetPageMovable(struct page *page, const struct movable_operations *ops);
106 void __ClearPageMovable(struct page *page);
107 #else
108 static inline bool PageMovable(struct page *page) { return false; }
109 static inline void __SetPageMovable(struct page *page,
110 const struct movable_operations *ops)
111 {
112 }
113 static inline void __ClearPageMovable(struct page *page)
114 {
115 }
116 #endif
117
118 static inline bool folio_test_movable(struct folio *folio)
119 {
120 return PageMovable(&folio->page);
121 }
122
123 static inline
124 const struct movable_operations *folio_movable_ops(struct folio *folio)
125 {
126 VM_BUG_ON(!__folio_test_movable(folio));
127
128 return (const struct movable_operations *)
129 ((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE);
130 }
131
132 static inline
133 const struct movable_operations *page_movable_ops(struct page *page)
134 {
135 VM_BUG_ON(!__PageMovable(page));
136
137 return (const struct movable_operations *)
138 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
139 }
140
141 #ifdef CONFIG_NUMA_BALANCING
142 int migrate_misplaced_folio_prepare(struct folio *folio,
143 struct vm_area_struct *vma, int node);
144 int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
145 int node);
146 #else
147 static inline int migrate_misplaced_folio_prepare(struct folio *folio,
148 struct vm_area_struct *vma, int node)
149 {
150 return -EAGAIN; /* can't migrate now */
151 }
152 static inline int migrate_misplaced_folio(struct folio *folio,
153 struct vm_area_struct *vma, int node)
154 {
155 return -EAGAIN; /* can't migrate now */
156 }
157 #endif /* CONFIG_NUMA_BALANCING */
158
159 #ifdef CONFIG_MIGRATION
160
161 /*
162 * Watch out for PAE architecture, which has an unsigned long, and might not
163 * have enough bits to store all physical address and flags. So far we have
164 * enough room for all our flags.
165 */
166 #define MIGRATE_PFN_VALID (1UL << 0)
167 #define MIGRATE_PFN_MIGRATE (1UL << 1)
168 #define MIGRATE_PFN_WRITE (1UL << 3)
169 #define MIGRATE_PFN_SHIFT 6
170
171 static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
172 {
173 if (!(mpfn & MIGRATE_PFN_VALID))
174 return NULL;
175 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
176 }
177
178 static inline unsigned long migrate_pfn(unsigned long pfn)
179 {
180 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
181 }
182
183 enum migrate_vma_direction {
184 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
185 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
186 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
187 };
188
189 struct migrate_vma {
190 struct vm_area_struct *vma;
191 /*
192 * Both src and dst array must be big enough for
193 * (end - start) >> PAGE_SHIFT entries.
194 *
195 * The src array must not be modified by the caller after
196 * migrate_vma_setup(), and must not change the dst array after
197 * migrate_vma_pages() returns.
198 */
199 unsigned long *dst;
200 unsigned long *src;
201 unsigned long cpages;
202 unsigned long npages;
203 unsigned long start;
204 unsigned long end;
205
206 /*
207 * Set to the owner value also stored in page->pgmap->owner for
208 * migrating out of device private memory. The flags also need to
209 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
210 * The caller should always set this field when using mmu notifier
211 * callbacks to avoid device MMU invalidations for device private
212 * pages that are not being migrated.
213 */
214 void *pgmap_owner;
215 unsigned long flags;
216
217 /*
218 * Set to vmf->page if this is being called to migrate a page as part of
219 * a migrate_to_ram() callback.
220 */
221 struct page *fault_page;
222 };
223
224 int migrate_vma_setup(struct migrate_vma *args);
225 void migrate_vma_pages(struct migrate_vma *migrate);
226 void migrate_vma_finalize(struct migrate_vma *migrate);
227 int migrate_device_range(unsigned long *src_pfns, unsigned long start,
228 unsigned long npages);
229 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns,
230 unsigned long npages);
231 void migrate_device_finalize(unsigned long *src_pfns,
232 unsigned long *dst_pfns, unsigned long npages);
233
234 #endif /* CONFIG_MIGRATION */
235
236 #endif /* _LINUX_MIGRATE_H */
237
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