4 * Declarations for Reverse Mapping functions in mm/rmap.c
7 #include <linux/list.h>
8 #include <linux/slab.h>
10 #include <linux/mutex.h>
11 #include <linux/memcontrol.h>
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.
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.
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.
28 struct anon_vma
*root
; /* Root of this anon_vma tree */
29 struct mutex mutex
; /* Serialize access to vma list */
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
40 * NOTE: the LSB of the head.next is set by
41 * mm_take_all_locks() _after_ taking the above lock. So the
42 * head 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).
47 struct list_head head
; /* Chain of private "related" vmas */
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.
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 "same_anon_vma" list contains the anon_vma_chains
61 * which link all the VMAs associated with this anon_vma.
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 list_head same_anon_vma
; /* locked by anon_vma->mutex */
71 static inline void get_anon_vma(struct anon_vma
*anon_vma
)
73 atomic_inc(&anon_vma
->refcount
);
76 void __put_anon_vma(struct anon_vma
*anon_vma
);
78 static inline void put_anon_vma(struct anon_vma
*anon_vma
)
80 if (atomic_dec_and_test(&anon_vma
->refcount
))
81 __put_anon_vma(anon_vma
);
84 static inline struct anon_vma
*page_anon_vma(struct page
*page
)
86 if (((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) !=
89 return page_rmapping(page
);
92 static inline void vma_lock_anon_vma(struct vm_area_struct
*vma
)
94 struct anon_vma
*anon_vma
= vma
->anon_vma
;
96 mutex_lock(&anon_vma
->root
->mutex
);
99 static inline void vma_unlock_anon_vma(struct vm_area_struct
*vma
)
101 struct anon_vma
*anon_vma
= vma
->anon_vma
;
103 mutex_unlock(&anon_vma
->root
->mutex
);
106 static inline void anon_vma_lock(struct anon_vma
*anon_vma
)
108 mutex_lock(&anon_vma
->root
->mutex
);
111 static inline void anon_vma_unlock(struct anon_vma
*anon_vma
)
113 mutex_unlock(&anon_vma
->root
->mutex
);
117 * anon_vma helper functions.
119 void anon_vma_init(void); /* create anon_vma_cachep */
120 int anon_vma_prepare(struct vm_area_struct
*);
121 void unlink_anon_vmas(struct vm_area_struct
*);
122 int anon_vma_clone(struct vm_area_struct
*, struct vm_area_struct
*);
123 int anon_vma_fork(struct vm_area_struct
*, struct vm_area_struct
*);
124 void __anon_vma_link(struct vm_area_struct
*);
126 static inline void anon_vma_merge(struct vm_area_struct
*vma
,
127 struct vm_area_struct
*next
)
129 VM_BUG_ON(vma
->anon_vma
!= next
->anon_vma
);
130 unlink_anon_vmas(next
);
133 struct anon_vma
*page_get_anon_vma(struct page
*page
);
136 * rmap interfaces called when adding or removing pte of page
138 void page_move_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
139 void page_add_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
140 void do_page_add_anon_rmap(struct page
*, struct vm_area_struct
*,
142 void page_add_new_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
143 void page_add_file_rmap(struct page
*);
144 void page_remove_rmap(struct page
*);
146 void hugepage_add_anon_rmap(struct page
*, struct vm_area_struct
*,
148 void hugepage_add_new_anon_rmap(struct page
*, struct vm_area_struct
*,
151 static inline void page_dup_rmap(struct page
*page
)
153 atomic_inc(&page
->_mapcount
);
157 * Called from mm/vmscan.c to handle paging out
159 int page_referenced(struct page
*, int is_locked
,
160 struct mem_cgroup
*cnt
, unsigned long *vm_flags
);
161 int page_referenced_one(struct page
*, struct vm_area_struct
*,
162 unsigned long address
, unsigned int *mapcount
, unsigned long *vm_flags
);
165 TTU_UNMAP
= 0, /* unmap mode */
166 TTU_MIGRATION
= 1, /* migration mode */
167 TTU_MUNLOCK
= 2, /* munlock mode */
168 TTU_ACTION_MASK
= 0xff,
170 TTU_IGNORE_MLOCK
= (1 << 8), /* ignore mlock */
171 TTU_IGNORE_ACCESS
= (1 << 9), /* don't age */
172 TTU_IGNORE_HWPOISON
= (1 << 10),/* corrupted page is recoverable */
174 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
176 bool is_vma_temporary_stack(struct vm_area_struct
*vma
);
178 int try_to_unmap(struct page
*, enum ttu_flags flags
);
179 int try_to_unmap_one(struct page
*, struct vm_area_struct
*,
180 unsigned long address
, enum ttu_flags flags
);
183 * Called from mm/filemap_xip.c to unmap empty zero page
185 pte_t
*__page_check_address(struct page
*, struct mm_struct
*,
186 unsigned long, spinlock_t
**, int);
188 static inline pte_t
*page_check_address(struct page
*page
, struct mm_struct
*mm
,
189 unsigned long address
,
190 spinlock_t
**ptlp
, int sync
)
194 __cond_lock(*ptlp
, ptep
= __page_check_address(page
, mm
, address
,
200 * Used by swapoff to help locate where page is expected in vma.
202 unsigned long page_address_in_vma(struct page
*, struct vm_area_struct
*);
205 * Cleans the PTEs of shared mappings.
206 * (and since clean PTEs should also be readonly, write protects them too)
208 * returns the number of cleaned PTEs.
210 int page_mkclean(struct page
*);
213 * called in munlock()/munmap() path to check for other vmas holding
216 int try_to_munlock(struct page
*);
219 * Called by memory-failure.c to kill processes.
221 struct anon_vma
*page_lock_anon_vma(struct page
*page
);
222 void page_unlock_anon_vma(struct anon_vma
*anon_vma
);
223 int page_mapped_in_vma(struct page
*page
, struct vm_area_struct
*vma
);
226 * Called by migrate.c to remove migration ptes, but might be used more later.
228 int rmap_walk(struct page
*page
, int (*rmap_one
)(struct page
*,
229 struct vm_area_struct
*, unsigned long, void *), void *arg
);
231 #else /* !CONFIG_MMU */
233 #define anon_vma_init() do {} while (0)
234 #define anon_vma_prepare(vma) (0)
235 #define anon_vma_link(vma) do {} while (0)
237 static inline int page_referenced(struct page
*page
, int is_locked
,
238 struct mem_cgroup
*cnt
,
239 unsigned long *vm_flags
)
245 #define try_to_unmap(page, refs) SWAP_FAIL
247 static inline int page_mkclean(struct page
*page
)
253 #endif /* CONFIG_MMU */
256 * Return values of try_to_unmap
258 #define SWAP_SUCCESS 0
263 #endif /* _LINUX_RMAP_H */
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