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 #include <linux/highmem.h> 13 14 /* 15 * The anon_vma heads a list of private "related" vmas, to scan if 16 * an anonymous page pointing to this anon_vma needs to be unmapped: 17 * the vmas on the list will be related by forking, or by splitting. 18 * 19 * Since vmas come and go as they are split and merged (particularly 20 * in mprotect), the mapping field of an anonymous page cannot point 21 * directly to a vma: instead it points to an anon_vma, on whose list 22 * the related vmas can be easily linked or unlinked. 23 * 24 * After unlinking the last vma on the list, we must garbage collect 25 * the anon_vma object itself: we're guaranteed no page can be 26 * pointing to this anon_vma once its vma list is empty. 27 */ 28 struct anon_vma { 29 struct anon_vma *root; /* Root of this anon_vma tree */ 30 struct rw_semaphore rwsem; /* W: modification, R: walking the list */ 31 /* 32 * The refcount is taken on an anon_vma when there is no 33 * guarantee that the vma of page tables will exist for 34 * the duration of the operation. A caller that takes 35 * the reference is responsible for clearing up the 36 * anon_vma if they are the last user on release 37 */ 38 atomic_t refcount; 39 40 /* 41 * Count of child anon_vmas and VMAs which points to this anon_vma. 42 * 43 * This counter is used for making decision about reusing anon_vma 44 * instead of forking new one. See comments in function anon_vma_clone. 45 */ 46 unsigned degree; 47 48 struct anon_vma *parent; /* Parent of this anon_vma */ 49 50 /* 51 * NOTE: the LSB of the rb_root.rb_node is set by 52 * mm_take_all_locks() _after_ taking the above lock. So the 53 * rb_root must only be read/written after taking the above lock 54 * to be sure to see a valid next pointer. The LSB bit itself 55 * is serialized by a system wide lock only visible to 56 * mm_take_all_locks() (mm_all_locks_mutex). 57 */ 58 struct rb_root rb_root; /* Interval tree of private "related" vmas */ 59 }; 60 61 /* 62 * The copy-on-write semantics of fork mean that an anon_vma 63 * can become associated with multiple processes. Furthermore, 64 * each child process will have its own anon_vma, where new 65 * pages for that process are instantiated. 66 * 67 * This structure allows us to find the anon_vmas associated 68 * with a VMA, or the VMAs associated with an anon_vma. 69 * The "same_vma" list contains the anon_vma_chains linking 70 * all the anon_vmas associated with this VMA. 71 * The "rb" field indexes on an interval tree the anon_vma_chains 72 * which link all the VMAs associated with this anon_vma. 73 */ 74 struct anon_vma_chain { 75 struct vm_area_struct *vma; 76 struct anon_vma *anon_vma; 77 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */ 78 struct rb_node rb; /* locked by anon_vma->rwsem */ 79 unsigned long rb_subtree_last; 80 #ifdef CONFIG_DEBUG_VM_RB 81 unsigned long cached_vma_start, cached_vma_last; 82 #endif 83 }; 84 85 enum ttu_flags { 86 TTU_UNMAP = 1, /* unmap mode */ 87 TTU_MIGRATION = 2, /* migration mode */ 88 TTU_MUNLOCK = 4, /* munlock mode */ 89 TTU_LZFREE = 8, /* lazy free mode */ 90 TTU_SPLIT_HUGE_PMD = 16, /* split huge PMD if any */ 91 92 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 93 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 94 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 95 TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible 96 * and caller guarantees they will 97 * do a final flush if necessary */ 98 TTU_RMAP_LOCKED = (1 << 12) /* do not grab rmap lock: 99 * caller holds it */ 100 }; 101 102 #ifdef CONFIG_MMU 103 static inline void get_anon_vma(struct anon_vma *anon_vma) 104 { 105 atomic_inc(&anon_vma->refcount); 106 } 107 108 void __put_anon_vma(struct anon_vma *anon_vma); 109 110 static inline void put_anon_vma(struct anon_vma *anon_vma) 111 { 112 if (atomic_dec_and_test(&anon_vma->refcount)) 113 __put_anon_vma(anon_vma); 114 } 115 116 static inline void anon_vma_lock_write(struct anon_vma *anon_vma) 117 { 118 down_write(&anon_vma->root->rwsem); 119 } 120 121 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) 122 { 123 up_write(&anon_vma->root->rwsem); 124 } 125 126 static inline void anon_vma_lock_read(struct anon_vma *anon_vma) 127 { 128 down_read(&anon_vma->root->rwsem); 129 } 130 131 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) 132 { 133 up_read(&anon_vma->root->rwsem); 134 } 135 136 137 /* 138 * anon_vma helper functions. 139 */ 140 void anon_vma_init(void); /* create anon_vma_cachep */ 141 int __anon_vma_prepare(struct vm_area_struct *); 142 void unlink_anon_vmas(struct vm_area_struct *); 143 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 144 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 145 146 static inline int anon_vma_prepare(struct vm_area_struct *vma) 147 { 148 if (likely(vma->anon_vma)) 149 return 0; 150 151 return __anon_vma_prepare(vma); 152 } 153 154 static inline void anon_vma_merge(struct vm_area_struct *vma, 155 struct vm_area_struct *next) 156 { 157 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma); 158 unlink_anon_vmas(next); 159 } 160 161 struct anon_vma *page_get_anon_vma(struct page *page); 162 163 /* bitflags for do_page_add_anon_rmap() */ 164 #define RMAP_EXCLUSIVE 0x01 165 #define RMAP_COMPOUND 0x02 166 167 /* 168 * rmap interfaces called when adding or removing pte of page 169 */ 170 void page_move_anon_rmap(struct page *, struct vm_area_struct *); 171 void page_add_anon_rmap(struct page *, struct vm_area_struct *, 172 unsigned long, bool); 173 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 174 unsigned long, int); 175 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, 176 unsigned long, bool); 177 void page_add_file_rmap(struct page *, bool); 178 void page_remove_rmap(struct page *, bool); 179 180 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 181 unsigned long); 182 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 183 unsigned long); 184 185 static inline void page_dup_rmap(struct page *page, bool compound) 186 { 187 atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount); 188 } 189 190 /* 191 * Called from mm/vmscan.c to handle paging out 192 */ 193 int page_referenced(struct page *, int is_locked, 194 struct mem_cgroup *memcg, unsigned long *vm_flags); 195 196 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 197 198 int try_to_unmap(struct page *, enum ttu_flags flags); 199 200 /* Avoid racy checks */ 201 #define PVMW_SYNC (1 << 0) 202 /* Look for migarion entries rather than present PTEs */ 203 #define PVMW_MIGRATION (1 << 1) 204 205 struct page_vma_mapped_walk { 206 struct page *page; 207 struct vm_area_struct *vma; 208 unsigned long address; 209 pmd_t *pmd; 210 pte_t *pte; 211 spinlock_t *ptl; 212 unsigned int flags; 213 }; 214 215 static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw) 216 { 217 if (pvmw->pte) 218 pte_unmap(pvmw->pte); 219 if (pvmw->ptl) 220 spin_unlock(pvmw->ptl); 221 } 222 223 bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw); 224 225 /* 226 * Used by swapoff to help locate where page is expected in vma. 227 */ 228 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 229 230 /* 231 * Cleans the PTEs of shared mappings. 232 * (and since clean PTEs should also be readonly, write protects them too) 233 * 234 * returns the number of cleaned PTEs. 235 */ 236 int page_mkclean(struct page *); 237 238 /* 239 * called in munlock()/munmap() path to check for other vmas holding 240 * the page mlocked. 241 */ 242 int try_to_munlock(struct page *); 243 244 void remove_migration_ptes(struct page *old, struct page *new, bool locked); 245 246 /* 247 * Called by memory-failure.c to kill processes. 248 */ 249 struct anon_vma *page_lock_anon_vma_read(struct page *page); 250 void page_unlock_anon_vma_read(struct anon_vma *anon_vma); 251 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 252 253 /* 254 * rmap_walk_control: To control rmap traversing for specific needs 255 * 256 * arg: passed to rmap_one() and invalid_vma() 257 * rmap_one: executed on each vma where page is mapped 258 * done: for checking traversing termination condition 259 * anon_lock: for getting anon_lock by optimized way rather than default 260 * invalid_vma: for skipping uninterested vma 261 */ 262 struct rmap_walk_control { 263 void *arg; 264 int (*rmap_one)(struct page *page, struct vm_area_struct *vma, 265 unsigned long addr, void *arg); 266 int (*done)(struct page *page); 267 struct anon_vma *(*anon_lock)(struct page *page); 268 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); 269 }; 270 271 int rmap_walk(struct page *page, struct rmap_walk_control *rwc); 272 int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc); 273 274 #else /* !CONFIG_MMU */ 275 276 #define anon_vma_init() do {} while (0) 277 #define anon_vma_prepare(vma) (0) 278 #define anon_vma_link(vma) do {} while (0) 279 280 static inline int page_referenced(struct page *page, int is_locked, 281 struct mem_cgroup *memcg, 282 unsigned long *vm_flags) 283 { 284 *vm_flags = 0; 285 return 0; 286 } 287 288 #define try_to_unmap(page, refs) SWAP_FAIL 289 290 static inline int page_mkclean(struct page *page) 291 { 292 return 0; 293 } 294 295 296 #endif /* CONFIG_MMU */ 297 298 /* 299 * Return values of try_to_unmap 300 */ 301 #define SWAP_SUCCESS 0 302 #define SWAP_AGAIN 1 303 #define SWAP_FAIL 2 304 #define SWAP_MLOCK 3 305 #define SWAP_LZFREE 4 306 307 #endif /* _LINUX_RMAP_H */ 308