1 #ifndef _LINUX_RMAP_H 2 #define _LINUX_RMAP_H 3 /* 4 * Declarations for Reverse Mapping functions in mm/rmap.c 5 */ 6 7 #include <linux/list.h> 8 #include <linux/slab.h> 9 #include <linux/mm.h> 10 #include <linux/spinlock.h> 11 #include <linux/memcontrol.h> 12 13 /* 14 * The anon_vma heads a list of private "related" vmas, to scan if 15 * an anonymous page pointing to this anon_vma needs to be unmapped: 16 * the vmas on the list will be related by forking, or by splitting. 17 * 18 * Since vmas come and go as they are split and merged (particularly 19 * in mprotect), the mapping field of an anonymous page cannot point 20 * directly to a vma: instead it points to an anon_vma, on whose list 21 * the related vmas can be easily linked or unlinked. 22 * 23 * After unlinking the last vma on the list, we must garbage collect 24 * the anon_vma object itself: we're guaranteed no page can be 25 * pointing to this anon_vma once its vma list is empty. 26 */ 27 struct anon_vma { 28 spinlock_t lock; /* Serialize access to vma list */ 29 struct anon_vma *root; /* Root of this anon_vma tree */ 30 #if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) 31 32 /* 33 * The external_refcount is taken by either KSM or page migration 34 * to take a reference to an anon_vma when there is no 35 * guarantee that the vma of page tables will exist for 36 * the duration of the operation. A caller that takes 37 * the reference is responsible for clearing up the 38 * anon_vma if they are the last user on release 39 */ 40 atomic_t external_refcount; 41 #endif 42 /* 43 * NOTE: the LSB of the head.next is set by 44 * mm_take_all_locks() _after_ taking the above lock. So the 45 * head must only be read/written after taking the above lock 46 * to be sure to see a valid next pointer. The LSB bit itself 47 * is serialized by a system wide lock only visible to 48 * mm_take_all_locks() (mm_all_locks_mutex). 49 */ 50 struct list_head head; /* Chain of private "related" vmas */ 51 }; 52 53 /* 54 * The copy-on-write semantics of fork mean that an anon_vma 55 * can become associated with multiple processes. Furthermore, 56 * each child process will have its own anon_vma, where new 57 * pages for that process are instantiated. 58 * 59 * This structure allows us to find the anon_vmas associated 60 * with a VMA, or the VMAs associated with an anon_vma. 61 * The "same_vma" list contains the anon_vma_chains linking 62 * all the anon_vmas associated with this VMA. 63 * The "same_anon_vma" list contains the anon_vma_chains 64 * which link all the VMAs associated with this anon_vma. 65 */ 66 struct anon_vma_chain { 67 struct vm_area_struct *vma; 68 struct anon_vma *anon_vma; 69 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */ 70 struct list_head same_anon_vma; /* locked by anon_vma->lock */ 71 }; 72 73 #ifdef CONFIG_MMU 74 #if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) 75 static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma) 76 { 77 atomic_set(&anon_vma->external_refcount, 0); 78 } 79 80 static inline int anonvma_external_refcount(struct anon_vma *anon_vma) 81 { 82 return atomic_read(&anon_vma->external_refcount); 83 } 84 85 static inline void get_anon_vma(struct anon_vma *anon_vma) 86 { 87 atomic_inc(&anon_vma->external_refcount); 88 } 89 90 void drop_anon_vma(struct anon_vma *); 91 #else 92 static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma) 93 { 94 } 95 96 static inline int anonvma_external_refcount(struct anon_vma *anon_vma) 97 { 98 return 0; 99 } 100 101 static inline void get_anon_vma(struct anon_vma *anon_vma) 102 { 103 } 104 105 static inline void drop_anon_vma(struct anon_vma *anon_vma) 106 { 107 } 108 #endif /* CONFIG_KSM */ 109 110 static inline struct anon_vma *page_anon_vma(struct page *page) 111 { 112 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 113 PAGE_MAPPING_ANON) 114 return NULL; 115 return page_rmapping(page); 116 } 117 118 static inline void vma_lock_anon_vma(struct vm_area_struct *vma) 119 { 120 struct anon_vma *anon_vma = vma->anon_vma; 121 if (anon_vma) 122 spin_lock(&anon_vma->root->lock); 123 } 124 125 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma) 126 { 127 struct anon_vma *anon_vma = vma->anon_vma; 128 if (anon_vma) 129 spin_unlock(&anon_vma->root->lock); 130 } 131 132 static inline void anon_vma_lock(struct anon_vma *anon_vma) 133 { 134 spin_lock(&anon_vma->root->lock); 135 } 136 137 static inline void anon_vma_unlock(struct anon_vma *anon_vma) 138 { 139 spin_unlock(&anon_vma->root->lock); 140 } 141 142 /* 143 * anon_vma helper functions. 144 */ 145 void anon_vma_init(void); /* create anon_vma_cachep */ 146 int anon_vma_prepare(struct vm_area_struct *); 147 void unlink_anon_vmas(struct vm_area_struct *); 148 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 149 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 150 void __anon_vma_link(struct vm_area_struct *); 151 void anon_vma_free(struct anon_vma *); 152 153 static inline void anon_vma_merge(struct vm_area_struct *vma, 154 struct vm_area_struct *next) 155 { 156 VM_BUG_ON(vma->anon_vma != next->anon_vma); 157 unlink_anon_vmas(next); 158 } 159 160 /* 161 * rmap interfaces called when adding or removing pte of page 162 */ 163 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 164 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 165 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 166 unsigned long, int); 167 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 168 void page_add_file_rmap(struct page *); 169 void page_remove_rmap(struct page *); 170 171 static inline void page_dup_rmap(struct page *page) 172 { 173 atomic_inc(&page->_mapcount); 174 } 175 176 /* 177 * Called from mm/vmscan.c to handle paging out 178 */ 179 int page_referenced(struct page *, int is_locked, 180 struct mem_cgroup *cnt, unsigned long *vm_flags); 181 int page_referenced_one(struct page *, struct vm_area_struct *, 182 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags); 183 184 enum ttu_flags { 185 TTU_UNMAP = 0, /* unmap mode */ 186 TTU_MIGRATION = 1, /* migration mode */ 187 TTU_MUNLOCK = 2, /* munlock mode */ 188 TTU_ACTION_MASK = 0xff, 189 190 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 191 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 192 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 193 }; 194 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 195 196 int try_to_unmap(struct page *, enum ttu_flags flags); 197 int try_to_unmap_one(struct page *, struct vm_area_struct *, 198 unsigned long address, enum ttu_flags flags); 199 200 /* 201 * Called from mm/filemap_xip.c to unmap empty zero page 202 */ 203 pte_t *page_check_address(struct page *, struct mm_struct *, 204 unsigned long, spinlock_t **, int); 205 206 /* 207 * Used by swapoff to help locate where page is expected in vma. 208 */ 209 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 210 211 /* 212 * Cleans the PTEs of shared mappings. 213 * (and since clean PTEs should also be readonly, write protects them too) 214 * 215 * returns the number of cleaned PTEs. 216 */ 217 int page_mkclean(struct page *); 218 219 /* 220 * called in munlock()/munmap() path to check for other vmas holding 221 * the page mlocked. 222 */ 223 int try_to_munlock(struct page *); 224 225 /* 226 * Called by memory-failure.c to kill processes. 227 */ 228 struct anon_vma *page_lock_anon_vma(struct page *page); 229 void page_unlock_anon_vma(struct anon_vma *anon_vma); 230 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 231 232 /* 233 * Called by migrate.c to remove migration ptes, but might be used more later. 234 */ 235 int rmap_walk(struct page *page, int (*rmap_one)(struct page *, 236 struct vm_area_struct *, unsigned long, void *), void *arg); 237 238 #else /* !CONFIG_MMU */ 239 240 #define anon_vma_init() do {} while (0) 241 #define anon_vma_prepare(vma) (0) 242 #define anon_vma_link(vma) do {} while (0) 243 244 static inline int page_referenced(struct page *page, int is_locked, 245 struct mem_cgroup *cnt, 246 unsigned long *vm_flags) 247 { 248 *vm_flags = 0; 249 return 0; 250 } 251 252 #define try_to_unmap(page, refs) SWAP_FAIL 253 254 static inline int page_mkclean(struct page *page) 255 { 256 return 0; 257 } 258 259 260 #endif /* CONFIG_MMU */ 261 262 /* 263 * Return values of try_to_unmap 264 */ 265 #define SWAP_SUCCESS 0 266 #define SWAP_AGAIN 1 267 #define SWAP_FAIL 2 268 #define SWAP_MLOCK 3 269 270 #endif /* _LINUX_RMAP_H */ 271