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/spinlock.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 */ 27struct anon_vma { 28 spinlock_t lock; /* Serialize access to vma list */ 29 struct anon_vma *root; /* Root of this anon_vma tree */ 30#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) 31 32 /* 33 * The external_refcount is taken by either KSM or page migration 34 * to take a reference to an anon_vma when there is no 35 * guarantee that the vma of page tables will exist for 36 * the duration of the operation. A caller that takes 37 * the reference is responsible for clearing up the 38 * anon_vma if they are the last user on release 39 */ 40 atomic_t external_refcount; 41#endif 42 /* 43 * NOTE: the LSB of the head.next is set by 44 * mm_take_all_locks() _after_ taking the above lock. So the 45 * head must only be read/written after taking the above lock 46 * to be sure to see a valid next pointer. The LSB bit itself 47 * is serialized by a system wide lock only visible to 48 * mm_take_all_locks() (mm_all_locks_mutex). 49 */ 50 struct list_head head; /* Chain of private "related" vmas */ 51}; 52 53/* 54 * The copy-on-write semantics of fork mean that an anon_vma 55 * can become associated with multiple processes. Furthermore, 56 * each child process will have its own anon_vma, where new 57 * pages for that process are instantiated. 58 * 59 * This structure allows us to find the anon_vmas associated 60 * with a VMA, or the VMAs associated with an anon_vma. 61 * The "same_vma" list contains the anon_vma_chains linking 62 * all the anon_vmas associated with this VMA. 63 * The "same_anon_vma" list contains the anon_vma_chains 64 * which link all the VMAs associated with this anon_vma. 65 */ 66struct anon_vma_chain { 67 struct vm_area_struct *vma; 68 struct anon_vma *anon_vma; 69 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */ 70 struct list_head same_anon_vma; /* locked by anon_vma->lock */ 71}; 72 73#ifdef CONFIG_MMU 74#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) 75static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma) 76{ 77 atomic_set(&anon_vma->external_refcount, 0); 78} 79 80static inline int anonvma_external_refcount(struct anon_vma *anon_vma) 81{ 82 return atomic_read(&anon_vma->external_refcount); 83} 84 85static inline void get_anon_vma(struct anon_vma *anon_vma) 86{ 87 atomic_inc(&anon_vma->external_refcount); 88} 89 90void drop_anon_vma(struct anon_vma *); 91#else 92static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma) 93{ 94} 95 96static inline int anonvma_external_refcount(struct anon_vma *anon_vma) 97{ 98 return 0; 99} 100 101static inline void get_anon_vma(struct anon_vma *anon_vma) 102{ 103} 104 105static inline void drop_anon_vma(struct anon_vma *anon_vma) 106{ 107} 108#endif /* CONFIG_KSM */ 109 110static inline struct anon_vma *page_anon_vma(struct page *page) 111{ 112 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 113 PAGE_MAPPING_ANON) 114 return NULL; 115 return page_rmapping(page); 116} 117 118static inline void vma_lock_anon_vma(struct vm_area_struct *vma) 119{ 120 struct anon_vma *anon_vma = vma->anon_vma; 121 if (anon_vma) 122 spin_lock(&anon_vma->root->lock); 123} 124 125static inline void vma_unlock_anon_vma(struct vm_area_struct *vma) 126{ 127 struct anon_vma *anon_vma = vma->anon_vma; 128 if (anon_vma) 129 spin_unlock(&anon_vma->root->lock); 130} 131 132static inline void anon_vma_lock(struct anon_vma *anon_vma) 133{ 134 spin_lock(&anon_vma->root->lock); 135} 136 137static inline void anon_vma_unlock(struct anon_vma *anon_vma) 138{ 139 spin_unlock(&anon_vma->root->lock); 140} 141 142/* 143 * anon_vma helper functions. 144 */ 145void anon_vma_init(void); /* create anon_vma_cachep */ 146int anon_vma_prepare(struct vm_area_struct *); 147void unlink_anon_vmas(struct vm_area_struct *); 148int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 149int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 150void __anon_vma_link(struct vm_area_struct *); 151void anon_vma_free(struct anon_vma *); 152 153static inline void anon_vma_merge(struct vm_area_struct *vma, 154 struct vm_area_struct *next) 155{ 156 VM_BUG_ON(vma->anon_vma != next->anon_vma); 157 unlink_anon_vmas(next); 158} 159 160/* 161 * rmap interfaces called when adding or removing pte of page 162 */ 163void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 164void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 165void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 166 unsigned long, int); 167void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 168void page_add_file_rmap(struct page *); 169void page_remove_rmap(struct page *); 170 171void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 172 unsigned long); 173void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 174 unsigned long); 175 176static inline void page_dup_rmap(struct page *page) 177{ 178 atomic_inc(&page->_mapcount); 179} 180 181/* 182 * Called from mm/vmscan.c to handle paging out 183 */ 184int page_referenced(struct page *, int is_locked, 185 struct mem_cgroup *cnt, unsigned long *vm_flags); 186int page_referenced_one(struct page *, struct vm_area_struct *, 187 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags); 188 189enum ttu_flags { 190 TTU_UNMAP = 0, /* unmap mode */ 191 TTU_MIGRATION = 1, /* migration mode */ 192 TTU_MUNLOCK = 2, /* munlock mode */ 193 TTU_ACTION_MASK = 0xff, 194 195 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 196 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 197 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 198}; 199#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 200 201int try_to_unmap(struct page *, enum ttu_flags flags); 202int try_to_unmap_one(struct page *, struct vm_area_struct *, 203 unsigned long address, enum ttu_flags flags); 204 205/* 206 * Called from mm/filemap_xip.c to unmap empty zero page 207 */ 208pte_t *page_check_address(struct page *, struct mm_struct *, 209 unsigned long, spinlock_t **, int); 210 211/* 212 * Used by swapoff to help locate where page is expected in vma. 213 */ 214unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 215 216/* 217 * Cleans the PTEs of shared mappings. 218 * (and since clean PTEs should also be readonly, write protects them too) 219 * 220 * returns the number of cleaned PTEs. 221 */ 222int page_mkclean(struct page *); 223 224/* 225 * called in munlock()/munmap() path to check for other vmas holding 226 * the page mlocked. 227 */ 228int try_to_munlock(struct page *); 229 230/* 231 * Called by memory-failure.c to kill processes. 232 */ 233struct anon_vma *page_lock_anon_vma(struct page *page); 234void page_unlock_anon_vma(struct anon_vma *anon_vma); 235int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 236 237/* 238 * Called by migrate.c to remove migration ptes, but might be used more later. 239 */ 240int rmap_walk(struct page *page, int (*rmap_one)(struct page *, 241 struct vm_area_struct *, unsigned long, void *), void *arg); 242 243#else /* !CONFIG_MMU */ 244 245#define anon_vma_init() do {} while (0) 246#define anon_vma_prepare(vma) (0) 247#define anon_vma_link(vma) do {} while (0) 248 249static inline int page_referenced(struct page *page, int is_locked, 250 struct mem_cgroup *cnt, 251 unsigned long *vm_flags) 252{ 253 *vm_flags = 0; 254 return 0; 255} 256 257#define try_to_unmap(page, refs) SWAP_FAIL 258 259static inline int page_mkclean(struct page *page) 260{ 261 return 0; 262} 263 264 265#endif /* CONFIG_MMU */ 266 267/* 268 * Return values of try_to_unmap 269 */ 270#define SWAP_SUCCESS 0 271#define SWAP_AGAIN 1 272#define SWAP_FAIL 2 273#define SWAP_MLOCK 3 274 275#endif /* _LINUX_RMAP_H */ 276