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 74 int migrate_huge_page_move_mapping(struct address_space *mapping, 75 struct folio *dst, struct folio *src); 76 void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl) 77 __releases(ptl); 78 void folio_migrate_flags(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_folio_t new, 86 free_folio_t free, unsigned long private, 87 enum migrate_mode mode, int reason, unsigned int *ret_succeeded) 88 { return -ENOSYS; } 89 static inline struct folio *alloc_migration_target(struct folio *src, 90 unsigned long private) 91 { return NULL; } 92 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode) 93 { return false; } 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 #ifdef CONFIG_COMPACTION 104 bool PageMovable(struct page *page); 105 void __SetPageMovable(struct page *page, const struct movable_operations *ops); 106 void __ClearPageMovable(struct page *page); 107 #else 108 static inline bool PageMovable(struct page *page) { return false; } 109 static inline void __SetPageMovable(struct page *page, 110 const struct movable_operations *ops) 111 { 112 } 113 static inline void __ClearPageMovable(struct page *page) 114 { 115 } 116 #endif 117 118 static inline bool folio_test_movable(struct folio *folio) 119 { 120 return PageMovable(&folio->page); 121 } 122 123 static inline 124 const struct movable_operations *folio_movable_ops(struct folio *folio) 125 { 126 VM_BUG_ON(!__folio_test_movable(folio)); 127 128 return (const struct movable_operations *) 129 ((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE); 130 } 131 132 static inline 133 const struct movable_operations *page_movable_ops(struct page *page) 134 { 135 VM_BUG_ON(!__PageMovable(page)); 136 137 return (const struct movable_operations *) 138 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); 139 } 140 141 #ifdef CONFIG_NUMA_BALANCING 142 int migrate_misplaced_folio_prepare(struct folio *folio, 143 struct vm_area_struct *vma, int node); 144 int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma, 145 int node); 146 #else 147 static inline int migrate_misplaced_folio_prepare(struct folio *folio, 148 struct vm_area_struct *vma, int node) 149 { 150 return -EAGAIN; /* can't migrate now */ 151 } 152 static inline int migrate_misplaced_folio(struct folio *folio, 153 struct vm_area_struct *vma, int node) 154 { 155 return -EAGAIN; /* can't migrate now */ 156 } 157 #endif /* CONFIG_NUMA_BALANCING */ 158 159 #ifdef CONFIG_MIGRATION 160 161 /* 162 * Watch out for PAE architecture, which has an unsigned long, and might not 163 * have enough bits to store all physical address and flags. So far we have 164 * enough room for all our flags. 165 */ 166 #define MIGRATE_PFN_VALID (1UL << 0) 167 #define MIGRATE_PFN_MIGRATE (1UL << 1) 168 #define MIGRATE_PFN_WRITE (1UL << 3) 169 #define MIGRATE_PFN_SHIFT 6 170 171 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) 172 { 173 if (!(mpfn & MIGRATE_PFN_VALID)) 174 return NULL; 175 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT); 176 } 177 178 static inline unsigned long migrate_pfn(unsigned long pfn) 179 { 180 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; 181 } 182 183 enum migrate_vma_direction { 184 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, 185 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, 186 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, 187 }; 188 189 struct migrate_vma { 190 struct vm_area_struct *vma; 191 /* 192 * Both src and dst array must be big enough for 193 * (end - start) >> PAGE_SHIFT entries. 194 * 195 * The src array must not be modified by the caller after 196 * migrate_vma_setup(), and must not change the dst array after 197 * migrate_vma_pages() returns. 198 */ 199 unsigned long *dst; 200 unsigned long *src; 201 unsigned long cpages; 202 unsigned long npages; 203 unsigned long start; 204 unsigned long end; 205 206 /* 207 * Set to the owner value also stored in page->pgmap->owner for 208 * migrating out of device private memory. The flags also need to 209 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. 210 * The caller should always set this field when using mmu notifier 211 * callbacks to avoid device MMU invalidations for device private 212 * pages that are not being migrated. 213 */ 214 void *pgmap_owner; 215 unsigned long flags; 216 217 /* 218 * Set to vmf->page if this is being called to migrate a page as part of 219 * a migrate_to_ram() callback. 220 */ 221 struct page *fault_page; 222 }; 223 224 int migrate_vma_setup(struct migrate_vma *args); 225 void migrate_vma_pages(struct migrate_vma *migrate); 226 void migrate_vma_finalize(struct migrate_vma *migrate); 227 int migrate_device_range(unsigned long *src_pfns, unsigned long start, 228 unsigned long npages); 229 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns, 230 unsigned long npages); 231 void migrate_device_finalize(unsigned long *src_pfns, 232 unsigned long *dst_pfns, unsigned long npages); 233 234 #endif /* CONFIG_MIGRATION */ 235 236 #endif /* _LINUX_MIGRATE_H */ 237