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 rb_root.rb_node is set by 41 * mm_take_all_locks() _after_ taking the above lock. So the 42 * rb_root 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 rb_root rb_root; /* Interval tree 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 "rb" field indexes on an interval tree 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 rb_node rb; /* locked by anon_vma->mutex */ 68 unsigned long rb_subtree_last; 69 #ifdef CONFIG_DEBUG_VM_RB 70 unsigned long cached_vma_start, cached_vma_last; 71 #endif 72 }; 73 74 enum ttu_flags { 75 TTU_UNMAP = 0, /* unmap mode */ 76 TTU_MIGRATION = 1, /* migration mode */ 77 TTU_MUNLOCK = 2, /* munlock mode */ 78 TTU_ACTION_MASK = 0xff, 79 80 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 81 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 82 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 83 }; 84 85 #ifdef CONFIG_MMU 86 static inline void get_anon_vma(struct anon_vma *anon_vma) 87 { 88 atomic_inc(&anon_vma->refcount); 89 } 90 91 void __put_anon_vma(struct anon_vma *anon_vma); 92 93 static inline void put_anon_vma(struct anon_vma *anon_vma) 94 { 95 if (atomic_dec_and_test(&anon_vma->refcount)) 96 __put_anon_vma(anon_vma); 97 } 98 99 static inline struct anon_vma *page_anon_vma(struct page *page) 100 { 101 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 102 PAGE_MAPPING_ANON) 103 return NULL; 104 return page_rmapping(page); 105 } 106 107 static inline void vma_lock_anon_vma(struct vm_area_struct *vma) 108 { 109 struct anon_vma *anon_vma = vma->anon_vma; 110 if (anon_vma) 111 mutex_lock(&anon_vma->root->mutex); 112 } 113 114 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma) 115 { 116 struct anon_vma *anon_vma = vma->anon_vma; 117 if (anon_vma) 118 mutex_unlock(&anon_vma->root->mutex); 119 } 120 121 static inline void anon_vma_lock(struct anon_vma *anon_vma) 122 { 123 mutex_lock(&anon_vma->root->mutex); 124 } 125 126 static inline void anon_vma_unlock(struct anon_vma *anon_vma) 127 { 128 mutex_unlock(&anon_vma->root->mutex); 129 } 130 131 /* 132 * anon_vma helper functions. 133 */ 134 void anon_vma_init(void); /* create anon_vma_cachep */ 135 int anon_vma_prepare(struct vm_area_struct *); 136 void unlink_anon_vmas(struct vm_area_struct *); 137 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 138 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 139 140 static inline void anon_vma_merge(struct vm_area_struct *vma, 141 struct vm_area_struct *next) 142 { 143 VM_BUG_ON(vma->anon_vma != next->anon_vma); 144 unlink_anon_vmas(next); 145 } 146 147 struct anon_vma *page_get_anon_vma(struct page *page); 148 149 /* 150 * rmap interfaces called when adding or removing pte of page 151 */ 152 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 153 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 154 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 155 unsigned long, int); 156 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 157 void page_add_file_rmap(struct page *); 158 void page_remove_rmap(struct page *); 159 160 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 161 unsigned long); 162 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 163 unsigned long); 164 165 static inline void page_dup_rmap(struct page *page) 166 { 167 atomic_inc(&page->_mapcount); 168 } 169 170 /* 171 * Called from mm/vmscan.c to handle paging out 172 */ 173 int page_referenced(struct page *, int is_locked, 174 struct mem_cgroup *memcg, unsigned long *vm_flags); 175 int page_referenced_one(struct page *, struct vm_area_struct *, 176 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags); 177 178 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 179 180 int try_to_unmap(struct page *, enum ttu_flags flags); 181 int try_to_unmap_one(struct page *, struct vm_area_struct *, 182 unsigned long address, enum ttu_flags flags); 183 184 /* 185 * Called from mm/filemap_xip.c to unmap empty zero page 186 */ 187 pte_t *__page_check_address(struct page *, struct mm_struct *, 188 unsigned long, spinlock_t **, int); 189 190 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm, 191 unsigned long address, 192 spinlock_t **ptlp, int sync) 193 { 194 pte_t *ptep; 195 196 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address, 197 ptlp, sync)); 198 return ptep; 199 } 200 201 /* 202 * Used by swapoff to help locate where page is expected in vma. 203 */ 204 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 205 206 /* 207 * Cleans the PTEs of shared mappings. 208 * (and since clean PTEs should also be readonly, write protects them too) 209 * 210 * returns the number of cleaned PTEs. 211 */ 212 int page_mkclean(struct page *); 213 214 /* 215 * called in munlock()/munmap() path to check for other vmas holding 216 * the page mlocked. 217 */ 218 int try_to_munlock(struct page *); 219 220 /* 221 * Called by memory-failure.c to kill processes. 222 */ 223 struct anon_vma *page_lock_anon_vma(struct page *page); 224 void page_unlock_anon_vma(struct anon_vma *anon_vma); 225 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 226 227 /* 228 * Called by migrate.c to remove migration ptes, but might be used more later. 229 */ 230 int rmap_walk(struct page *page, int (*rmap_one)(struct page *, 231 struct vm_area_struct *, unsigned long, void *), void *arg); 232 233 #else /* !CONFIG_MMU */ 234 235 #define anon_vma_init() do {} while (0) 236 #define anon_vma_prepare(vma) (0) 237 #define anon_vma_link(vma) do {} while (0) 238 239 static inline int page_referenced(struct page *page, int is_locked, 240 struct mem_cgroup *memcg, 241 unsigned long *vm_flags) 242 { 243 *vm_flags = 0; 244 return 0; 245 } 246 247 #define try_to_unmap(page, refs) SWAP_FAIL 248 249 static inline int page_mkclean(struct page *page) 250 { 251 return 0; 252 } 253 254 255 #endif /* CONFIG_MMU */ 256 257 /* 258 * Return values of try_to_unmap 259 */ 260 #define SWAP_SUCCESS 0 261 #define SWAP_AGAIN 1 262 #define SWAP_FAIL 2 263 #define SWAP_MLOCK 3 264 265 #endif /* _LINUX_RMAP_H */ 266