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 22 /** 23 * struct movable_operations - Driver page migration 24 * @isolate_page: 25 * The VM calls this function to prepare the page to be moved. The page 26 * is locked and the driver should not unlock it. The driver should 27 * return ``true`` if the page is movable and ``false`` if it is not 28 * currently movable. After this function returns, the VM uses the 29 * page->lru field, so the driver must preserve any information which 30 * is usually stored here. 31 * 32 * @migrate_page: 33 * After isolation, the VM calls this function with the isolated 34 * @src page. The driver should copy the contents of the 35 * @src page to the @dst page and set up the fields of @dst page. 36 * Both pages are locked. 37 * If page migration is successful, the driver should call 38 * __ClearPageMovable(@src) and return MIGRATEPAGE_SUCCESS. 39 * If the driver cannot migrate the page at the moment, it can return 40 * -EAGAIN. The VM interprets this as a temporary migration failure and 41 * will retry it later. Any other error value is a permanent migration 42 * failure and migration will not be retried. 43 * The driver shouldn't touch the @src->lru field while in the 44 * migrate_page() function. It may write to @dst->lru. 45 * 46 * @putback_page: 47 * If migration fails on the isolated page, the VM informs the driver 48 * that the page is no longer a candidate for migration by calling 49 * this function. The driver should put the isolated page back into 50 * its own data structure. 51 */ 52 struct movable_operations { 53 bool (*isolate_page)(struct page *, isolate_mode_t); 54 int (*migrate_page)(struct page *dst, struct page *src, 55 enum migrate_mode); 56 void (*putback_page)(struct page *); 57 }; 58 59 /* Defined in mm/debug.c: */ 60 extern const char *migrate_reason_names[MR_TYPES]; 61 62 #ifdef CONFIG_MIGRATION 63 64 extern void putback_movable_pages(struct list_head *l); 65 int migrate_folio_extra(struct address_space *mapping, struct folio *dst, 66 struct folio *src, enum migrate_mode mode, int extra_count); 67 int migrate_folio(struct address_space *mapping, struct folio *dst, 68 struct folio *src, enum migrate_mode mode); 69 extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free, 70 unsigned long private, enum migrate_mode mode, int reason, 71 unsigned int *ret_succeeded); 72 extern struct page *alloc_migration_target(struct page *page, unsigned long private); 73 extern int isolate_movable_page(struct page *page, isolate_mode_t mode); 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, pte_t *ptep, 78 spinlock_t *ptl); 79 void folio_migrate_flags(struct folio *newfolio, struct folio *folio); 80 void folio_migrate_copy(struct folio *newfolio, struct folio *folio); 81 int folio_migrate_mapping(struct address_space *mapping, 82 struct folio *newfolio, struct folio *folio, int extra_count); 83 84 #else 85 86 static inline void putback_movable_pages(struct list_head *l) {} 87 static inline int migrate_pages(struct list_head *l, new_page_t new, 88 free_page_t free, unsigned long private, enum migrate_mode mode, 89 int reason, unsigned int *ret_succeeded) 90 { return -ENOSYS; } 91 static inline struct page *alloc_migration_target(struct page *page, 92 unsigned long private) 93 { return NULL; } 94 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode) 95 { return -EBUSY; } 96 97 static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 98 struct folio *dst, struct folio *src) 99 { 100 return -ENOSYS; 101 } 102 103 #endif /* CONFIG_MIGRATION */ 104 105 #ifdef CONFIG_COMPACTION 106 bool PageMovable(struct page *page); 107 void __SetPageMovable(struct page *page, const struct movable_operations *ops); 108 void __ClearPageMovable(struct page *page); 109 #else 110 static inline bool PageMovable(struct page *page) { return false; } 111 static inline void __SetPageMovable(struct page *page, 112 const struct movable_operations *ops) 113 { 114 } 115 static inline void __ClearPageMovable(struct page *page) 116 { 117 } 118 #endif 119 120 static inline bool folio_test_movable(struct folio *folio) 121 { 122 return PageMovable(&folio->page); 123 } 124 125 static inline 126 const struct movable_operations *folio_movable_ops(struct folio *folio) 127 { 128 VM_BUG_ON(!__folio_test_movable(folio)); 129 130 return (const struct movable_operations *) 131 ((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE); 132 } 133 134 static inline 135 const struct movable_operations *page_movable_ops(struct page *page) 136 { 137 VM_BUG_ON(!__PageMovable(page)); 138 139 return (const struct movable_operations *) 140 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); 141 } 142 143 #ifdef CONFIG_NUMA_BALANCING 144 extern int migrate_misplaced_page(struct page *page, 145 struct vm_area_struct *vma, int node); 146 #else 147 static inline int migrate_misplaced_page(struct page *page, 148 struct vm_area_struct *vma, int node) 149 { 150 return -EAGAIN; /* can't migrate now */ 151 } 152 #endif /* CONFIG_NUMA_BALANCING */ 153 154 #ifdef CONFIG_MIGRATION 155 156 /* 157 * Watch out for PAE architecture, which has an unsigned long, and might not 158 * have enough bits to store all physical address and flags. So far we have 159 * enough room for all our flags. 160 */ 161 #define MIGRATE_PFN_VALID (1UL << 0) 162 #define MIGRATE_PFN_MIGRATE (1UL << 1) 163 #define MIGRATE_PFN_WRITE (1UL << 3) 164 #define MIGRATE_PFN_SHIFT 6 165 166 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) 167 { 168 if (!(mpfn & MIGRATE_PFN_VALID)) 169 return NULL; 170 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT); 171 } 172 173 static inline unsigned long migrate_pfn(unsigned long pfn) 174 { 175 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; 176 } 177 178 enum migrate_vma_direction { 179 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, 180 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, 181 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, 182 }; 183 184 struct migrate_vma { 185 struct vm_area_struct *vma; 186 /* 187 * Both src and dst array must be big enough for 188 * (end - start) >> PAGE_SHIFT entries. 189 * 190 * The src array must not be modified by the caller after 191 * migrate_vma_setup(), and must not change the dst array after 192 * migrate_vma_pages() returns. 193 */ 194 unsigned long *dst; 195 unsigned long *src; 196 unsigned long cpages; 197 unsigned long npages; 198 unsigned long start; 199 unsigned long end; 200 201 /* 202 * Set to the owner value also stored in page->pgmap->owner for 203 * migrating out of device private memory. The flags also need to 204 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. 205 * The caller should always set this field when using mmu notifier 206 * callbacks to avoid device MMU invalidations for device private 207 * pages that are not being migrated. 208 */ 209 void *pgmap_owner; 210 unsigned long flags; 211 212 /* 213 * Set to vmf->page if this is being called to migrate a page as part of 214 * a migrate_to_ram() callback. 215 */ 216 struct page *fault_page; 217 }; 218 219 int migrate_vma_setup(struct migrate_vma *args); 220 void migrate_vma_pages(struct migrate_vma *migrate); 221 void migrate_vma_finalize(struct migrate_vma *migrate); 222 int migrate_device_range(unsigned long *src_pfns, unsigned long start, 223 unsigned long npages); 224 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns, 225 unsigned long npages); 226 void migrate_device_finalize(unsigned long *src_pfns, 227 unsigned long *dst_pfns, unsigned long npages); 228 229 #endif /* CONFIG_MIGRATION */ 230 231 #endif /* _LINUX_MIGRATE_H */ 232