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 extern int migrate_page(struct address_space *mapping, 66 struct page *newpage, struct page *page, 67 enum migrate_mode mode); 68 extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free, 69 unsigned long private, enum migrate_mode mode, int reason, 70 unsigned int *ret_succeeded); 71 extern struct page *alloc_migration_target(struct page *page, unsigned long private); 72 extern int isolate_movable_page(struct page *page, isolate_mode_t mode); 73 74 extern void migrate_page_states(struct page *newpage, struct page *page); 75 extern void migrate_page_copy(struct page *newpage, struct page *page); 76 extern int migrate_huge_page_move_mapping(struct address_space *mapping, 77 struct page *newpage, struct page *page); 78 extern int migrate_page_move_mapping(struct address_space *mapping, 79 struct page *newpage, struct page *page, int extra_count); 80 void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep, 81 spinlock_t *ptl); 82 void folio_migrate_flags(struct folio *newfolio, struct folio *folio); 83 void folio_migrate_copy(struct folio *newfolio, struct folio *folio); 84 int folio_migrate_mapping(struct address_space *mapping, 85 struct folio *newfolio, struct folio *folio, int extra_count); 86 87 #else 88 89 static inline void putback_movable_pages(struct list_head *l) {} 90 static inline int migrate_pages(struct list_head *l, new_page_t new, 91 free_page_t free, unsigned long private, enum migrate_mode mode, 92 int reason, unsigned int *ret_succeeded) 93 { return -ENOSYS; } 94 static inline struct page *alloc_migration_target(struct page *page, 95 unsigned long private) 96 { return NULL; } 97 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode) 98 { return -EBUSY; } 99 100 static inline void migrate_page_states(struct page *newpage, struct page *page) 101 { 102 } 103 104 static inline void migrate_page_copy(struct page *newpage, 105 struct page *page) {} 106 107 static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 108 struct page *newpage, struct page *page) 109 { 110 return -ENOSYS; 111 } 112 113 #endif /* CONFIG_MIGRATION */ 114 115 #if defined(CONFIG_MIGRATION) && defined(CONFIG_NUMA) 116 extern void set_migration_target_nodes(void); 117 extern void migrate_on_reclaim_init(void); 118 extern bool numa_demotion_enabled; 119 extern int next_demotion_node(int node); 120 #else 121 static inline void set_migration_target_nodes(void) {} 122 static inline void migrate_on_reclaim_init(void) {} 123 static inline int next_demotion_node(int node) 124 { 125 return NUMA_NO_NODE; 126 } 127 #define numa_demotion_enabled false 128 #endif 129 130 #ifdef CONFIG_COMPACTION 131 bool PageMovable(struct page *page); 132 void __SetPageMovable(struct page *page, const struct movable_operations *ops); 133 void __ClearPageMovable(struct page *page); 134 #else 135 static inline bool PageMovable(struct page *page) { return false; } 136 static inline void __SetPageMovable(struct page *page, 137 const struct movable_operations *ops) 138 { 139 } 140 static inline void __ClearPageMovable(struct page *page) 141 { 142 } 143 #endif 144 145 static inline bool folio_test_movable(struct folio *folio) 146 { 147 return PageMovable(&folio->page); 148 } 149 150 static inline 151 const struct movable_operations *page_movable_ops(struct page *page) 152 { 153 VM_BUG_ON(!__PageMovable(page)); 154 155 return (const struct movable_operations *) 156 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); 157 } 158 159 #ifdef CONFIG_NUMA_BALANCING 160 extern int migrate_misplaced_page(struct page *page, 161 struct vm_area_struct *vma, int node); 162 #else 163 static inline int migrate_misplaced_page(struct page *page, 164 struct vm_area_struct *vma, int node) 165 { 166 return -EAGAIN; /* can't migrate now */ 167 } 168 #endif /* CONFIG_NUMA_BALANCING */ 169 170 #ifdef CONFIG_MIGRATION 171 172 /* 173 * Watch out for PAE architecture, which has an unsigned long, and might not 174 * have enough bits to store all physical address and flags. So far we have 175 * enough room for all our flags. 176 */ 177 #define MIGRATE_PFN_VALID (1UL << 0) 178 #define MIGRATE_PFN_MIGRATE (1UL << 1) 179 #define MIGRATE_PFN_WRITE (1UL << 3) 180 #define MIGRATE_PFN_SHIFT 6 181 182 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) 183 { 184 if (!(mpfn & MIGRATE_PFN_VALID)) 185 return NULL; 186 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT); 187 } 188 189 static inline unsigned long migrate_pfn(unsigned long pfn) 190 { 191 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; 192 } 193 194 enum migrate_vma_direction { 195 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, 196 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, 197 }; 198 199 struct migrate_vma { 200 struct vm_area_struct *vma; 201 /* 202 * Both src and dst array must be big enough for 203 * (end - start) >> PAGE_SHIFT entries. 204 * 205 * The src array must not be modified by the caller after 206 * migrate_vma_setup(), and must not change the dst array after 207 * migrate_vma_pages() returns. 208 */ 209 unsigned long *dst; 210 unsigned long *src; 211 unsigned long cpages; 212 unsigned long npages; 213 unsigned long start; 214 unsigned long end; 215 216 /* 217 * Set to the owner value also stored in page->pgmap->owner for 218 * migrating out of device private memory. The flags also need to 219 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. 220 * The caller should always set this field when using mmu notifier 221 * callbacks to avoid device MMU invalidations for device private 222 * pages that are not being migrated. 223 */ 224 void *pgmap_owner; 225 unsigned long flags; 226 }; 227 228 int migrate_vma_setup(struct migrate_vma *args); 229 void migrate_vma_pages(struct migrate_vma *migrate); 230 void migrate_vma_finalize(struct migrate_vma *migrate); 231 #endif /* CONFIG_MIGRATION */ 232 233 #endif /* _LINUX_MIGRATE_H */ 234