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