include/linux/migrate.h

   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 bool isolate_folio_to_list(struct folio *folio, struct list_head *list);
  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, spinlock_t *ptl)
  78                 __releases(ptl);
  79 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
  80 int folio_migrate_mapping(struct address_space *mapping,
  81                 struct folio *newfolio, struct folio *folio, int extra_count);
  82
  83 #else
  84
  85 static inline void putback_movable_pages(struct list_head *l) {}
  86 static inline int migrate_pages(struct list_head *l, new_folio_t new,
  87                 free_folio_t free, unsigned long private,
  88                 enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
  89         { return -ENOSYS; }
  90 static inline struct folio *alloc_migration_target(struct folio *src,
  91                 unsigned long private)
  92         { return NULL; }
  93 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
  94         { return false; }
  95 static inline bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
  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         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         return (const struct movable_operations *)
 132                 ((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         return (const struct movable_operations *)
 141                 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
 142 }
 143
 144 #ifdef CONFIG_NUMA_BALANCING
 145 int migrate_misplaced_folio_prepare(struct folio *folio,
 146                 struct vm_area_struct *vma, int node);
 147 int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
 148                            int node);
 149 #else
 150 static inline int migrate_misplaced_folio_prepare(struct folio *folio,
 151                 struct vm_area_struct *vma, int node)
 152 {
 153         return -EAGAIN; /* can't migrate now */
 154 }
 155 static inline int migrate_misplaced_folio(struct folio *folio,
 156                                          struct vm_area_struct *vma, int node)
 157 {
 158         return -EAGAIN; /* can't migrate now */
 159 }
 160 #endif /* CONFIG_NUMA_BALANCING */
 161
 162 #ifdef CONFIG_MIGRATION
 163
 164 /*
 165  * Watch out for PAE architecture, which has an unsigned long, and might not
 166  * have enough bits to store all physical address and flags. So far we have
 167  * enough room for all our flags.
 168  */
 169 #define MIGRATE_PFN_VALID       (1UL << 0)
 170 #define MIGRATE_PFN_MIGRATE     (1UL << 1)
 171 #define MIGRATE_PFN_WRITE       (1UL << 3)
 172 #define MIGRATE_PFN_SHIFT       6
 173
 174 static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
 175 {
 176         if (!(mpfn & MIGRATE_PFN_VALID))
 177                 return NULL;
 178         return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
 179 }
 180
 181 static inline unsigned long migrate_pfn(unsigned long pfn)
 182 {
 183         return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
 184 }
 185
 186 enum migrate_vma_direction {
 187         MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
 188         MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
 189         MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
 190 };
 191
 192 struct migrate_vma {
 193         struct vm_area_struct   *vma;
 194         /*
 195          * Both src and dst array must be big enough for
 196          * (end - start) >> PAGE_SHIFT entries.
 197          *
 198          * The src array must not be modified by the caller after
 199          * migrate_vma_setup(), and must not change the dst array after
 200          * migrate_vma_pages() returns.
 201          */
 202         unsigned long           *dst;
 203         unsigned long           *src;
 204         unsigned long           cpages;
 205         unsigned long           npages;
 206         unsigned long           start;
 207         unsigned long           end;
 208
 209         /*
 210          * Set to the owner value also stored in page->pgmap->owner for
 211          * migrating out of device private memory. The flags also need to
 212          * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
 213          * The caller should always set this field when using mmu notifier
 214          * callbacks to avoid device MMU invalidations for device private
 215          * pages that are not being migrated.
 216          */
 217         void                    *pgmap_owner;
 218         unsigned long           flags;
 219
 220         /*
 221          * Set to vmf->page if this is being called to migrate a page as part of
 222          * a migrate_to_ram() callback.
 223          */
 224         struct page             *fault_page;
 225 };
 226
 227 int migrate_vma_setup(struct migrate_vma *args);
 228 void migrate_vma_pages(struct migrate_vma *migrate);
 229 void migrate_vma_finalize(struct migrate_vma *migrate);
 230 int migrate_device_range(unsigned long *src_pfns, unsigned long start,
 231                         unsigned long npages);
 232 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns,
 233                         unsigned long npages);
 234 void migrate_device_finalize(unsigned long *src_pfns,
 235                         unsigned long *dst_pfns, unsigned long npages);
 236
 237 #endif /* CONFIG_MIGRATION */
 238
 239 #endif /* _LINUX_MIGRATE_H */