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