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 int migrate_huge_page_move_mapping(struct address_space *mapping, 74 struct folio *dst, struct folio *src); 75 void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep, 76 spinlock_t *ptl); 77 void folio_migrate_flags(struct folio *newfolio, struct folio *folio); 78 void folio_migrate_copy(struct folio *newfolio, struct folio *folio); 79 int folio_migrate_mapping(struct address_space *mapping, 80 struct folio *newfolio, struct folio *folio, int extra_count); 81 82 #else 83 84 static inline void putback_movable_pages(struct list_head *l) {} 85 static inline int migrate_pages(struct list_head *l, new_page_t new, 86 free_page_t free, unsigned long private, enum migrate_mode mode, 87 int reason, unsigned int *ret_succeeded) 88 { return -ENOSYS; } 89 static inline struct page *alloc_migration_target(struct page *page, 90 unsigned long private) 91 { return NULL; } 92 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode) 93 { return -EBUSY; } 94 95 static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 96 struct folio *dst, struct folio *src) 97 { 98 return -ENOSYS; 99 } 100 101 #endif /* CONFIG_MIGRATION */ 102 103 #if defined(CONFIG_MIGRATION) && defined(CONFIG_NUMA) 104 extern void set_migration_target_nodes(void); 105 extern void migrate_on_reclaim_init(void); 106 extern bool numa_demotion_enabled; 107 extern int next_demotion_node(int node); 108 #else 109 static inline void set_migration_target_nodes(void) {} 110 static inline void migrate_on_reclaim_init(void) {} 111 static inline int next_demotion_node(int node) 112 { 113 return NUMA_NO_NODE; 114 } 115 #define numa_demotion_enabled false 116 #endif 117 118 #ifdef CONFIG_COMPACTION 119 bool PageMovable(struct page *page); 120 void __SetPageMovable(struct page *page, const struct movable_operations *ops); 121 void __ClearPageMovable(struct page *page); 122 #else 123 static inline bool PageMovable(struct page *page) { return false; } 124 static inline void __SetPageMovable(struct page *page, 125 const struct movable_operations *ops) 126 { 127 } 128 static inline void __ClearPageMovable(struct page *page) 129 { 130 } 131 #endif 132 133 static inline bool folio_test_movable(struct folio *folio) 134 { 135 return PageMovable(&folio->page); 136 } 137 138 static inline 139 const struct movable_operations *page_movable_ops(struct page *page) 140 { 141 VM_BUG_ON(!__PageMovable(page)); 142 143 return (const struct movable_operations *) 144 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); 145 } 146 147 #ifdef CONFIG_NUMA_BALANCING 148 extern int migrate_misplaced_page(struct page *page, 149 struct vm_area_struct *vma, int node); 150 #else 151 static inline int migrate_misplaced_page(struct page *page, 152 struct vm_area_struct *vma, int node) 153 { 154 return -EAGAIN; /* can't migrate now */ 155 } 156 #endif /* CONFIG_NUMA_BALANCING */ 157 158 #ifdef CONFIG_MIGRATION 159 160 /* 161 * Watch out for PAE architecture, which has an unsigned long, and might not 162 * have enough bits to store all physical address and flags. So far we have 163 * enough room for all our flags. 164 */ 165 #define MIGRATE_PFN_VALID (1UL << 0) 166 #define MIGRATE_PFN_MIGRATE (1UL << 1) 167 #define MIGRATE_PFN_WRITE (1UL << 3) 168 #define MIGRATE_PFN_SHIFT 6 169 170 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) 171 { 172 if (!(mpfn & MIGRATE_PFN_VALID)) 173 return NULL; 174 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT); 175 } 176 177 static inline unsigned long migrate_pfn(unsigned long pfn) 178 { 179 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; 180 } 181 182 enum migrate_vma_direction { 183 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, 184 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, 185 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, 186 }; 187 188 struct migrate_vma { 189 struct vm_area_struct *vma; 190 /* 191 * Both src and dst array must be big enough for 192 * (end - start) >> PAGE_SHIFT entries. 193 * 194 * The src array must not be modified by the caller after 195 * migrate_vma_setup(), and must not change the dst array after 196 * migrate_vma_pages() returns. 197 */ 198 unsigned long *dst; 199 unsigned long *src; 200 unsigned long cpages; 201 unsigned long npages; 202 unsigned long start; 203 unsigned long end; 204 205 /* 206 * Set to the owner value also stored in page->pgmap->owner for 207 * migrating out of device private memory. The flags also need to 208 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. 209 * The caller should always set this field when using mmu notifier 210 * callbacks to avoid device MMU invalidations for device private 211 * pages that are not being migrated. 212 */ 213 void *pgmap_owner; 214 unsigned long flags; 215 }; 216 217 int migrate_vma_setup(struct migrate_vma *args); 218 void migrate_vma_pages(struct migrate_vma *migrate); 219 void migrate_vma_finalize(struct migrate_vma *migrate); 220 #endif /* CONFIG_MIGRATION */ 221 222 #endif /* _LINUX_MIGRATE_H */ 223