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 * Count of child anon_vmas and VMAs which points to this anon_vma. 41 * 42 * This counter is used for making decision about reusing anon_vma 43 * instead of forking new one. See comments in function anon_vma_clone. 44 */ 45 unsigned degree; 46 47 struct anon_vma *parent; /* Parent of this anon_vma */ 48 49 /* 50 * NOTE: the LSB of the rb_root.rb_node is set by 51 * mm_take_all_locks() _after_ taking the above lock. So the 52 * rb_root must only be read/written after taking the above lock 53 * to be sure to see a valid next pointer. The LSB bit itself 54 * is serialized by a system wide lock only visible to 55 * mm_take_all_locks() (mm_all_locks_mutex). 56 */ 57 struct rb_root rb_root; /* Interval tree of private "related" vmas */ 58 }; 59 60 /* 61 * The copy-on-write semantics of fork mean that an anon_vma 62 * can become associated with multiple processes. Furthermore, 63 * each child process will have its own anon_vma, where new 64 * pages for that process are instantiated. 65 * 66 * This structure allows us to find the anon_vmas associated 67 * with a VMA, or the VMAs associated with an anon_vma. 68 * The "same_vma" list contains the anon_vma_chains linking 69 * all the anon_vmas associated with this VMA. 70 * The "rb" field indexes on an interval tree the anon_vma_chains 71 * which link all the VMAs associated with this anon_vma. 72 */ 73 struct anon_vma_chain { 74 struct vm_area_struct *vma; 75 struct anon_vma *anon_vma; 76 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */ 77 struct rb_node rb; /* locked by anon_vma->rwsem */ 78 unsigned long rb_subtree_last; 79 #ifdef CONFIG_DEBUG_VM_RB 80 unsigned long cached_vma_start, cached_vma_last; 81 #endif 82 }; 83 84 enum ttu_flags { 85 TTU_UNMAP = 1, /* unmap mode */ 86 TTU_MIGRATION = 2, /* migration mode */ 87 TTU_MUNLOCK = 4, /* munlock mode */ 88 TTU_LZFREE = 8, /* lazy free mode */ 89 TTU_SPLIT_HUGE_PMD = 16, /* split huge PMD if any */ 90 91 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 92 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 93 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 94 TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible 95 * and caller guarantees they will 96 * do a final flush if necessary */ 97 TTU_RMAP_LOCKED = (1 << 12) /* do not grab rmap lock: 98 * caller holds it */ 99 }; 100 101 #ifdef CONFIG_MMU 102 static inline void get_anon_vma(struct anon_vma *anon_vma) 103 { 104 atomic_inc(&anon_vma->refcount); 105 } 106 107 void __put_anon_vma(struct anon_vma *anon_vma); 108 109 static inline void put_anon_vma(struct anon_vma *anon_vma) 110 { 111 if (atomic_dec_and_test(&anon_vma->refcount)) 112 __put_anon_vma(anon_vma); 113 } 114 115 static inline void anon_vma_lock_write(struct anon_vma *anon_vma) 116 { 117 down_write(&anon_vma->root->rwsem); 118 } 119 120 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) 121 { 122 up_write(&anon_vma->root->rwsem); 123 } 124 125 static inline void anon_vma_lock_read(struct anon_vma *anon_vma) 126 { 127 down_read(&anon_vma->root->rwsem); 128 } 129 130 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) 131 { 132 up_read(&anon_vma->root->rwsem); 133 } 134 135 136 /* 137 * anon_vma helper functions. 138 */ 139 void anon_vma_init(void); /* create anon_vma_cachep */ 140 int anon_vma_prepare(struct vm_area_struct *); 141 void unlink_anon_vmas(struct vm_area_struct *); 142 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 143 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 144 145 static inline void anon_vma_merge(struct vm_area_struct *vma, 146 struct vm_area_struct *next) 147 { 148 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma); 149 unlink_anon_vmas(next); 150 } 151 152 struct anon_vma *page_get_anon_vma(struct page *page); 153 154 /* bitflags for do_page_add_anon_rmap() */ 155 #define RMAP_EXCLUSIVE 0x01 156 #define RMAP_COMPOUND 0x02 157 158 /* 159 * rmap interfaces called when adding or removing pte of page 160 */ 161 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 162 void page_add_anon_rmap(struct page *, struct vm_area_struct *, 163 unsigned long, bool); 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 *, 167 unsigned long, bool); 168 void page_add_file_rmap(struct page *); 169 void page_remove_rmap(struct page *, bool); 170 171 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 172 unsigned long); 173 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 174 unsigned long); 175 176 static inline void page_dup_rmap(struct page *page, bool compound) 177 { 178 atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount); 179 } 180 181 /* 182 * Called from mm/vmscan.c to handle paging out 183 */ 184 int page_referenced(struct page *, int is_locked, 185 struct mem_cgroup *memcg, unsigned long *vm_flags); 186 187 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 188 189 int try_to_unmap(struct page *, enum ttu_flags flags); 190 191 /* 192 * Used by uprobes to replace a userspace page safely 193 */ 194 pte_t *__page_check_address(struct page *, struct mm_struct *, 195 unsigned long, spinlock_t **, int); 196 197 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm, 198 unsigned long address, 199 spinlock_t **ptlp, int sync) 200 { 201 pte_t *ptep; 202 203 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address, 204 ptlp, sync)); 205 return ptep; 206 } 207 208 /* 209 * Used by idle page tracking to check if a page was referenced via page 210 * tables. 211 */ 212 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 213 bool page_check_address_transhuge(struct page *page, struct mm_struct *mm, 214 unsigned long address, pmd_t **pmdp, 215 pte_t **ptep, spinlock_t **ptlp); 216 #else 217 static inline bool page_check_address_transhuge(struct page *page, 218 struct mm_struct *mm, unsigned long address, 219 pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp) 220 { 221 *ptep = page_check_address(page, mm, address, ptlp, 0); 222 *pmdp = NULL; 223 return !!*ptep; 224 } 225 #endif 226 227 /* 228 * Used by swapoff to help locate where page is expected in vma. 229 */ 230 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 231 232 /* 233 * Cleans the PTEs of shared mappings. 234 * (and since clean PTEs should also be readonly, write protects them too) 235 * 236 * returns the number of cleaned PTEs. 237 */ 238 int page_mkclean(struct page *); 239 240 /* 241 * called in munlock()/munmap() path to check for other vmas holding 242 * the page mlocked. 243 */ 244 int try_to_munlock(struct page *); 245 246 void remove_migration_ptes(struct page *old, struct page *new, bool locked); 247 248 /* 249 * Called by memory-failure.c to kill processes. 250 */ 251 struct anon_vma *page_lock_anon_vma_read(struct page *page); 252 void page_unlock_anon_vma_read(struct anon_vma *anon_vma); 253 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 254 255 /* 256 * rmap_walk_control: To control rmap traversing for specific needs 257 * 258 * arg: passed to rmap_one() and invalid_vma() 259 * rmap_one: executed on each vma where page is mapped 260 * done: for checking traversing termination condition 261 * anon_lock: for getting anon_lock by optimized way rather than default 262 * invalid_vma: for skipping uninterested vma 263 */ 264 struct rmap_walk_control { 265 void *arg; 266 int (*rmap_one)(struct page *page, struct vm_area_struct *vma, 267 unsigned long addr, void *arg); 268 int (*done)(struct page *page); 269 struct anon_vma *(*anon_lock)(struct page *page); 270 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); 271 }; 272 273 int rmap_walk(struct page *page, struct rmap_walk_control *rwc); 274 int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc); 275 276 #else /* !CONFIG_MMU */ 277 278 #define anon_vma_init() do {} while (0) 279 #define anon_vma_prepare(vma) (0) 280 #define anon_vma_link(vma) do {} while (0) 281 282 static inline int page_referenced(struct page *page, int is_locked, 283 struct mem_cgroup *memcg, 284 unsigned long *vm_flags) 285 { 286 *vm_flags = 0; 287 return 0; 288 } 289 290 #define try_to_unmap(page, refs) SWAP_FAIL 291 292 static inline int page_mkclean(struct page *page) 293 { 294 return 0; 295 } 296 297 298 #endif /* CONFIG_MMU */ 299 300 /* 301 * Return values of try_to_unmap 302 */ 303 #define SWAP_SUCCESS 0 304 #define SWAP_AGAIN 1 305 #define SWAP_FAIL 2 306 #define SWAP_MLOCK 3 307 #define SWAP_LZFREE 4 308 309 #endif /* _LINUX_RMAP_H */ 310