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 bool isolate_folio_to_list(struct folio *folio, struct list_head *list); 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, spinlock_t *ptl) 78 __releases(ptl); 79 void folio_migrate_flags(struct folio *newfolio, struct folio *folio); 80 int folio_migrate_mapping(struct address_space *mapping, 81 struct folio *newfolio, struct folio *folio, int extra_count); 82 83 #else 84 putback_movable_pages(struct list_head * l)85 static inline void putback_movable_pages(struct list_head *l) {} migrate_pages(struct list_head * l,new_folio_t new,free_folio_t free,unsigned long private,enum migrate_mode mode,int reason,unsigned int * ret_succeeded)86 static inline int migrate_pages(struct list_head *l, new_folio_t new, 87 free_folio_t free, unsigned long private, 88 enum migrate_mode mode, int reason, unsigned int *ret_succeeded) 89 { return -ENOSYS; } alloc_migration_target(struct folio * src,unsigned long private)90 static inline struct folio *alloc_migration_target(struct folio *src, 91 unsigned long private) 92 { return NULL; } isolate_movable_page(struct page * page,isolate_mode_t mode)93 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode) 94 { return false; } isolate_folio_to_list(struct folio * folio,struct list_head * list)95 static inline bool isolate_folio_to_list(struct folio *folio, struct list_head *list) 96 { return false; } 97 migrate_huge_page_move_mapping(struct address_space * mapping,struct folio * dst,struct folio * src)98 static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 99 struct folio *dst, struct folio *src) 100 { 101 return -ENOSYS; 102 } 103 104 #endif /* CONFIG_MIGRATION */ 105 106 #ifdef CONFIG_COMPACTION 107 bool PageMovable(struct page *page); 108 void __SetPageMovable(struct page *page, const struct movable_operations *ops); 109 void __ClearPageMovable(struct page *page); 110 #else PageMovable(struct page * page)111 static inline bool PageMovable(struct page *page) { return false; } __SetPageMovable(struct page * page,const struct movable_operations * ops)112 static inline void __SetPageMovable(struct page *page, 113 const struct movable_operations *ops) 114 { 115 } __ClearPageMovable(struct page * page)116 static inline void __ClearPageMovable(struct page *page) 117 { 118 } 119 #endif 120 folio_test_movable(struct folio * folio)121 static inline bool folio_test_movable(struct folio *folio) 122 { 123 return PageMovable(&folio->page); 124 } 125 126 static inline folio_movable_ops(struct folio * folio)127 const struct movable_operations *folio_movable_ops(struct folio *folio) 128 { 129 VM_BUG_ON(!__folio_test_movable(folio)); 130 131 return (const struct movable_operations *) 132 ((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE); 133 } 134 135 static inline page_movable_ops(struct page * page)136 const struct movable_operations *page_movable_ops(struct page *page) 137 { 138 VM_BUG_ON(!__PageMovable(page)); 139 140 return (const struct movable_operations *) 141 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); 142 } 143 144 #ifdef CONFIG_NUMA_BALANCING 145 int migrate_misplaced_folio_prepare(struct folio *folio, 146 struct vm_area_struct *vma, int node); 147 int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma, 148 int node); 149 #else migrate_misplaced_folio_prepare(struct folio * folio,struct vm_area_struct * vma,int node)150 static inline int migrate_misplaced_folio_prepare(struct folio *folio, 151 struct vm_area_struct *vma, int node) 152 { 153 return -EAGAIN; /* can't migrate now */ 154 } migrate_misplaced_folio(struct folio * folio,struct vm_area_struct * vma,int node)155 static inline int migrate_misplaced_folio(struct folio *folio, 156 struct vm_area_struct *vma, int node) 157 { 158 return -EAGAIN; /* can't migrate now */ 159 } 160 #endif /* CONFIG_NUMA_BALANCING */ 161 162 #ifdef CONFIG_MIGRATION 163 164 /* 165 * Watch out for PAE architecture, which has an unsigned long, and might not 166 * have enough bits to store all physical address and flags. So far we have 167 * enough room for all our flags. 168 */ 169 #define MIGRATE_PFN_VALID (1UL << 0) 170 #define MIGRATE_PFN_MIGRATE (1UL << 1) 171 #define MIGRATE_PFN_WRITE (1UL << 3) 172 #define MIGRATE_PFN_SHIFT 6 173 migrate_pfn_to_page(unsigned long mpfn)174 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) 175 { 176 if (!(mpfn & MIGRATE_PFN_VALID)) 177 return NULL; 178 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT); 179 } 180 migrate_pfn(unsigned long pfn)181 static inline unsigned long migrate_pfn(unsigned long pfn) 182 { 183 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; 184 } 185 186 enum migrate_vma_direction { 187 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, 188 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, 189 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, 190 }; 191 192 struct migrate_vma { 193 struct vm_area_struct *vma; 194 /* 195 * Both src and dst array must be big enough for 196 * (end - start) >> PAGE_SHIFT entries. 197 * 198 * The src array must not be modified by the caller after 199 * migrate_vma_setup(), and must not change the dst array after 200 * migrate_vma_pages() returns. 201 */ 202 unsigned long *dst; 203 unsigned long *src; 204 unsigned long cpages; 205 unsigned long npages; 206 unsigned long start; 207 unsigned long end; 208 209 /* 210 * Set to the owner value also stored in page->pgmap->owner for 211 * migrating out of device private memory. The flags also need to 212 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. 213 * The caller should always set this field when using mmu notifier 214 * callbacks to avoid device MMU invalidations for device private 215 * pages that are not being migrated. 216 */ 217 void *pgmap_owner; 218 unsigned long flags; 219 220 /* 221 * Set to vmf->page if this is being called to migrate a page as part of 222 * a migrate_to_ram() callback. 223 */ 224 struct page *fault_page; 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 int migrate_device_range(unsigned long *src_pfns, unsigned long start, 231 unsigned long npages); 232 void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns, 233 unsigned long npages); 234 void migrate_device_finalize(unsigned long *src_pfns, 235 unsigned long *dst_pfns, unsigned long npages); 236 237 #endif /* CONFIG_MIGRATION */ 238 239 #endif /* _LINUX_MIGRATE_H */ 240