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(struct address_space *mapping, struct folio *dst, 66 struct folio *src, enum migrate_mode mode); 67 extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free, 68 unsigned long private, enum migrate_mode mode, int reason, 69 unsigned int *ret_succeeded); 70 extern struct page *alloc_migration_target(struct page *page, unsigned long private); 71 extern int isolate_movable_page(struct page *page, isolate_mode_t mode); 72 73 extern void migrate_page_states(struct page *newpage, struct page *page); 74 extern void migrate_page_copy(struct page *newpage, struct page *page); 75 int migrate_huge_page_move_mapping(struct address_space *mapping, 76 struct folio *dst, struct folio *src); 77 extern int migrate_page_move_mapping(struct address_space *mapping, 78 struct page *newpage, struct page *page, int extra_count); 79 void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep, 80 spinlock_t *ptl); 81 void folio_migrate_flags(struct folio *newfolio, struct folio *folio); 82 void folio_migrate_copy(struct folio *newfolio, struct folio *folio); 83 int folio_migrate_mapping(struct address_space *mapping, 84 struct folio *newfolio, struct folio *folio, int extra_count); 85 86 #else 87 88 static inline void putback_movable_pages(struct list_head *l) {} 89 static inline int migrate_pages(struct list_head *l, new_page_t new, 90 free_page_t free, unsigned long private, enum migrate_mode mode, 91 int reason, unsigned int *ret_succeeded) 92 { return -ENOSYS; } 93 static inline struct page *alloc_migration_target(struct page *page, 94 unsigned long private) 95 { return NULL; } 96 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode) 97 { return -EBUSY; } 98 99 static inline void migrate_page_states(struct page *newpage, struct page *page) 100 { 101 } 102 103 static inline void migrate_page_copy(struct page *newpage, 104 struct page *page) {} 105 106 static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 107 struct folio *dst, struct folio *src) 108 { 109 return -ENOSYS; 110 } 111 112 #endif /* CONFIG_MIGRATION */ 113 114 #if defined(CONFIG_MIGRATION) && defined(CONFIG_NUMA) 115 extern void set_migration_target_nodes(void); 116 extern void migrate_on_reclaim_init(void); 117 extern bool numa_demotion_enabled; 118 extern int next_demotion_node(int node); 119 #else 120 static inline void set_migration_target_nodes(void) {} 121 static inline void migrate_on_reclaim_init(void) {} 122 static inline int next_demotion_node(int node) 123 { 124 return NUMA_NO_NODE; 125 } 126 #define numa_demotion_enabled false 127 #endif 128 129 #ifdef CONFIG_COMPACTION 130 bool PageMovable(struct page *page); 131 void __SetPageMovable(struct page *page, const struct movable_operations *ops); 132 void __ClearPageMovable(struct page *page); 133 #else 134 static inline bool PageMovable(struct page *page) { return false; } 135 static inline void __SetPageMovable(struct page *page, 136 const struct movable_operations *ops) 137 { 138 } 139 static inline void __ClearPageMovable(struct page *page) 140 { 141 } 142 #endif 143 144 static inline bool folio_test_movable(struct folio *folio) 145 { 146 return PageMovable(&folio->page); 147 } 148 149 static inline 150 const struct movable_operations *page_movable_ops(struct page *page) 151 { 152 VM_BUG_ON(!__PageMovable(page)); 153 154 return (const struct movable_operations *) 155 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); 156 } 157 158 #ifdef CONFIG_NUMA_BALANCING 159 extern int migrate_misplaced_page(struct page *page, 160 struct vm_area_struct *vma, int node); 161 #else 162 static inline int migrate_misplaced_page(struct page *page, 163 struct vm_area_struct *vma, int node) 164 { 165 return -EAGAIN; /* can't migrate now */ 166 } 167 #endif /* CONFIG_NUMA_BALANCING */ 168 169 #ifdef CONFIG_MIGRATION 170 171 /* 172 * Watch out for PAE architecture, which has an unsigned long, and might not 173 * have enough bits to store all physical address and flags. So far we have 174 * enough room for all our flags. 175 */ 176 #define MIGRATE_PFN_VALID (1UL << 0) 177 #define MIGRATE_PFN_MIGRATE (1UL << 1) 178 #define MIGRATE_PFN_WRITE (1UL << 3) 179 #define MIGRATE_PFN_SHIFT 6 180 181 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) 182 { 183 if (!(mpfn & MIGRATE_PFN_VALID)) 184 return NULL; 185 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT); 186 } 187 188 static inline unsigned long migrate_pfn(unsigned long pfn) 189 { 190 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; 191 } 192 193 enum migrate_vma_direction { 194 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, 195 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, 196 }; 197 198 struct migrate_vma { 199 struct vm_area_struct *vma; 200 /* 201 * Both src and dst array must be big enough for 202 * (end - start) >> PAGE_SHIFT entries. 203 * 204 * The src array must not be modified by the caller after 205 * migrate_vma_setup(), and must not change the dst array after 206 * migrate_vma_pages() returns. 207 */ 208 unsigned long *dst; 209 unsigned long *src; 210 unsigned long cpages; 211 unsigned long npages; 212 unsigned long start; 213 unsigned long end; 214 215 /* 216 * Set to the owner value also stored in page->pgmap->owner for 217 * migrating out of device private memory. The flags also need to 218 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. 219 * The caller should always set this field when using mmu notifier 220 * callbacks to avoid device MMU invalidations for device private 221 * pages that are not being migrated. 222 */ 223 void *pgmap_owner; 224 unsigned long flags; 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 #endif /* CONFIG_MIGRATION */ 231 232 #endif /* _LINUX_MIGRATE_H */ 233