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/rwsem.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 rw_semaphore rwsem; /* W: modification, R: walking the 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->rwsem */ 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 = 1, /* unmap mode */ 76 TTU_MIGRATION = 2, /* migration mode */ 77 TTU_MUNLOCK = 4, /* munlock mode */ 78 79 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 80 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 81 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 82 }; 83 84 #ifdef CONFIG_MMU 85 static inline void get_anon_vma(struct anon_vma *anon_vma) 86 { 87 atomic_inc(&anon_vma->refcount); 88 } 89 90 void __put_anon_vma(struct anon_vma *anon_vma); 91 92 static inline void put_anon_vma(struct anon_vma *anon_vma) 93 { 94 if (atomic_dec_and_test(&anon_vma->refcount)) 95 __put_anon_vma(anon_vma); 96 } 97 98 static inline struct anon_vma *page_anon_vma(struct page *page) 99 { 100 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 101 PAGE_MAPPING_ANON) 102 return NULL; 103 return page_rmapping(page); 104 } 105 106 static inline void vma_lock_anon_vma(struct vm_area_struct *vma) 107 { 108 struct anon_vma *anon_vma = vma->anon_vma; 109 if (anon_vma) 110 down_write(&anon_vma->root->rwsem); 111 } 112 113 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma) 114 { 115 struct anon_vma *anon_vma = vma->anon_vma; 116 if (anon_vma) 117 up_write(&anon_vma->root->rwsem); 118 } 119 120 static inline void anon_vma_lock_write(struct anon_vma *anon_vma) 121 { 122 down_write(&anon_vma->root->rwsem); 123 } 124 125 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) 126 { 127 up_write(&anon_vma->root->rwsem); 128 } 129 130 static inline void anon_vma_lock_read(struct anon_vma *anon_vma) 131 { 132 down_read(&anon_vma->root->rwsem); 133 } 134 135 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) 136 { 137 up_read(&anon_vma->root->rwsem); 138 } 139 140 141 /* 142 * anon_vma helper functions. 143 */ 144 void anon_vma_init(void); /* create anon_vma_cachep */ 145 int anon_vma_prepare(struct vm_area_struct *); 146 void unlink_anon_vmas(struct vm_area_struct *); 147 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 148 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 149 150 static inline void anon_vma_merge(struct vm_area_struct *vma, 151 struct vm_area_struct *next) 152 { 153 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma); 154 unlink_anon_vmas(next); 155 } 156 157 struct anon_vma *page_get_anon_vma(struct page *page); 158 159 /* 160 * rmap interfaces called when adding or removing pte of page 161 */ 162 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 163 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 164 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 165 unsigned long, int); 166 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 167 void page_add_file_rmap(struct page *); 168 void page_remove_rmap(struct page *); 169 170 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 171 unsigned long); 172 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 173 unsigned long); 174 175 static inline void page_dup_rmap(struct page *page) 176 { 177 atomic_inc(&page->_mapcount); 178 } 179 180 /* 181 * Called from mm/vmscan.c to handle paging out 182 */ 183 int page_referenced(struct page *, int is_locked, 184 struct mem_cgroup *memcg, unsigned long *vm_flags); 185 186 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 187 188 int try_to_unmap(struct page *, enum ttu_flags flags); 189 190 /* 191 * Called from mm/filemap_xip.c to unmap empty zero page 192 */ 193 pte_t *__page_check_address(struct page *, struct mm_struct *, 194 unsigned long, spinlock_t **, int); 195 196 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm, 197 unsigned long address, 198 spinlock_t **ptlp, int sync) 199 { 200 pte_t *ptep; 201 202 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address, 203 ptlp, sync)); 204 return ptep; 205 } 206 207 /* 208 * Used by swapoff to help locate where page is expected in vma. 209 */ 210 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 211 212 /* 213 * Cleans the PTEs of shared mappings. 214 * (and since clean PTEs should also be readonly, write protects them too) 215 * 216 * returns the number of cleaned PTEs. 217 */ 218 int page_mkclean(struct page *); 219 220 /* 221 * called in munlock()/munmap() path to check for other vmas holding 222 * the page mlocked. 223 */ 224 int try_to_munlock(struct page *); 225 226 /* 227 * Called by memory-failure.c to kill processes. 228 */ 229 struct anon_vma *page_lock_anon_vma_read(struct page *page); 230 void page_unlock_anon_vma_read(struct anon_vma *anon_vma); 231 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 232 233 /* 234 * rmap_walk_control: To control rmap traversing for specific needs 235 * 236 * arg: passed to rmap_one() and invalid_vma() 237 * rmap_one: executed on each vma where page is mapped 238 * done: for checking traversing termination condition 239 * file_nonlinear: for handling file nonlinear mapping 240 * anon_lock: for getting anon_lock by optimized way rather than default 241 * invalid_vma: for skipping uninterested vma 242 */ 243 struct rmap_walk_control { 244 void *arg; 245 int (*rmap_one)(struct page *page, struct vm_area_struct *vma, 246 unsigned long addr, void *arg); 247 int (*done)(struct page *page); 248 int (*file_nonlinear)(struct page *, struct address_space *, void *arg); 249 struct anon_vma *(*anon_lock)(struct page *page); 250 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); 251 }; 252 253 int rmap_walk(struct page *page, struct rmap_walk_control *rwc); 254 255 #else /* !CONFIG_MMU */ 256 257 #define anon_vma_init() do {} while (0) 258 #define anon_vma_prepare(vma) (0) 259 #define anon_vma_link(vma) do {} while (0) 260 261 static inline int page_referenced(struct page *page, int is_locked, 262 struct mem_cgroup *memcg, 263 unsigned long *vm_flags) 264 { 265 *vm_flags = 0; 266 return 0; 267 } 268 269 #define try_to_unmap(page, refs) SWAP_FAIL 270 271 static inline int page_mkclean(struct page *page) 272 { 273 return 0; 274 } 275 276 277 #endif /* CONFIG_MMU */ 278 279 /* 280 * Return values of try_to_unmap 281 */ 282 #define SWAP_SUCCESS 0 283 #define SWAP_AGAIN 1 284 #define SWAP_FAIL 2 285 #define SWAP_MLOCK 3 286 287 #endif /* _LINUX_RMAP_H */ 288