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_MIGRATION = 0x1, /* migration mode */ 87 TTU_MUNLOCK = 0x2, /* munlock mode */ 88 89 TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */ 90 TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */ 91 TTU_IGNORE_ACCESS = 0x10, /* don't age */ 92 TTU_IGNORE_HWPOISON = 0x20, /* corrupted page is recoverable */ 93 TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible 94 * and caller guarantees they will 95 * do a final flush if necessary */ 96 TTU_RMAP_LOCKED = 0x80 /* do not grab rmap lock: 97 * caller holds it */ 98 }; 99 100 #ifdef CONFIG_MMU 101 static inline void get_anon_vma(struct anon_vma *anon_vma) 102 { 103 atomic_inc(&anon_vma->refcount); 104 } 105 106 void __put_anon_vma(struct anon_vma *anon_vma); 107 108 static inline void put_anon_vma(struct anon_vma *anon_vma) 109 { 110 if (atomic_dec_and_test(&anon_vma->refcount)) 111 __put_anon_vma(anon_vma); 112 } 113 114 static inline void anon_vma_lock_write(struct anon_vma *anon_vma) 115 { 116 down_write(&anon_vma->root->rwsem); 117 } 118 119 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) 120 { 121 up_write(&anon_vma->root->rwsem); 122 } 123 124 static inline void anon_vma_lock_read(struct anon_vma *anon_vma) 125 { 126 down_read(&anon_vma->root->rwsem); 127 } 128 129 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) 130 { 131 up_read(&anon_vma->root->rwsem); 132 } 133 134 135 /* 136 * anon_vma helper functions. 137 */ 138 void anon_vma_init(void); /* create anon_vma_cachep */ 139 int __anon_vma_prepare(struct vm_area_struct *); 140 void unlink_anon_vmas(struct vm_area_struct *); 141 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 142 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 143 144 static inline int anon_vma_prepare(struct vm_area_struct *vma) 145 { 146 if (likely(vma->anon_vma)) 147 return 0; 148 149 return __anon_vma_prepare(vma); 150 } 151 152 static inline void anon_vma_merge(struct vm_area_struct *vma, 153 struct vm_area_struct *next) 154 { 155 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma); 156 unlink_anon_vmas(next); 157 } 158 159 struct anon_vma *page_get_anon_vma(struct page *page); 160 161 /* bitflags for do_page_add_anon_rmap() */ 162 #define RMAP_EXCLUSIVE 0x01 163 #define RMAP_COMPOUND 0x02 164 165 /* 166 * rmap interfaces called when adding or removing pte of page 167 */ 168 void page_move_anon_rmap(struct page *, struct vm_area_struct *); 169 void page_add_anon_rmap(struct page *, struct vm_area_struct *, 170 unsigned long, bool); 171 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 172 unsigned long, int); 173 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, 174 unsigned long, bool); 175 void page_add_file_rmap(struct page *, bool); 176 void page_remove_rmap(struct page *, bool); 177 178 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 179 unsigned long); 180 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 181 unsigned long); 182 183 static inline void page_dup_rmap(struct page *page, bool compound) 184 { 185 atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount); 186 } 187 188 /* 189 * Called from mm/vmscan.c to handle paging out 190 */ 191 int page_referenced(struct page *, int is_locked, 192 struct mem_cgroup *memcg, unsigned long *vm_flags); 193 194 bool try_to_unmap(struct page *, enum ttu_flags flags); 195 196 /* Avoid racy checks */ 197 #define PVMW_SYNC (1 << 0) 198 /* Look for migarion entries rather than present PTEs */ 199 #define PVMW_MIGRATION (1 << 1) 200 201 struct page_vma_mapped_walk { 202 struct page *page; 203 struct vm_area_struct *vma; 204 unsigned long address; 205 pmd_t *pmd; 206 pte_t *pte; 207 spinlock_t *ptl; 208 unsigned int flags; 209 }; 210 211 static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw) 212 { 213 if (pvmw->pte) 214 pte_unmap(pvmw->pte); 215 if (pvmw->ptl) 216 spin_unlock(pvmw->ptl); 217 } 218 219 bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw); 220 221 /* 222 * Used by swapoff to help locate where page is expected in vma. 223 */ 224 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 225 226 /* 227 * Cleans the PTEs of shared mappings. 228 * (and since clean PTEs should also be readonly, write protects them too) 229 * 230 * returns the number of cleaned PTEs. 231 */ 232 int page_mkclean(struct page *); 233 234 /* 235 * called in munlock()/munmap() path to check for other vmas holding 236 * the page mlocked. 237 */ 238 void try_to_munlock(struct page *); 239 240 void remove_migration_ptes(struct page *old, struct page *new, bool locked); 241 242 /* 243 * Called by memory-failure.c to kill processes. 244 */ 245 struct anon_vma *page_lock_anon_vma_read(struct page *page); 246 void page_unlock_anon_vma_read(struct anon_vma *anon_vma); 247 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 248 249 /* 250 * rmap_walk_control: To control rmap traversing for specific needs 251 * 252 * arg: passed to rmap_one() and invalid_vma() 253 * rmap_one: executed on each vma where page is mapped 254 * done: for checking traversing termination condition 255 * anon_lock: for getting anon_lock by optimized way rather than default 256 * invalid_vma: for skipping uninterested vma 257 */ 258 struct rmap_walk_control { 259 void *arg; 260 /* 261 * Return false if page table scanning in rmap_walk should be stopped. 262 * Otherwise, return true. 263 */ 264 bool (*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 void rmap_walk(struct page *page, struct rmap_walk_control *rwc); 272 void 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) false 289 290 static inline int page_mkclean(struct page *page) 291 { 292 return 0; 293 } 294 295 296 #endif /* CONFIG_MMU */ 297 298 #endif /* _LINUX_RMAP_H */ 299