4 * Declarations for Reverse Mapping functions in mm/rmap.c
7 #include <linux/list.h>
8 #include <linux/slab.h>
10 #include <linux/spinlock.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 spinlock_t lock
; /* Serialize access to vma list */
30 atomic_t ksm_refcount
;
33 * NOTE: the LSB of the head.next is set by
34 * mm_take_all_locks() _after_ taking the above lock. So the
35 * head must only be read/written after taking the above lock
36 * to be sure to see a valid next pointer. The LSB bit itself
37 * is serialized by a system wide lock only visible to
38 * mm_take_all_locks() (mm_all_locks_mutex).
40 struct list_head head
; /* Chain of private "related" vmas */
44 * The copy-on-write semantics of fork mean that an anon_vma
45 * can become associated with multiple processes. Furthermore,
46 * each child process will have its own anon_vma, where new
47 * pages for that process are instantiated.
49 * This structure allows us to find the anon_vmas associated
50 * with a VMA, or the VMAs associated with an anon_vma.
51 * The "same_vma" list contains the anon_vma_chains linking
52 * all the anon_vmas associated with this VMA.
53 * The "same_anon_vma" list contains the anon_vma_chains
54 * which link all the VMAs associated with this anon_vma.
56 struct anon_vma_chain
{
57 struct vm_area_struct
*vma
;
58 struct anon_vma
*anon_vma
;
59 struct list_head same_vma
; /* locked by mmap_sem & page_table_lock */
60 struct list_head same_anon_vma
; /* locked by anon_vma->lock */
65 static inline void ksm_refcount_init(struct anon_vma
*anon_vma
)
67 atomic_set(&anon_vma
->ksm_refcount
, 0);
70 static inline int ksm_refcount(struct anon_vma
*anon_vma
)
72 return atomic_read(&anon_vma
->ksm_refcount
);
75 static inline void ksm_refcount_init(struct anon_vma
*anon_vma
)
79 static inline int ksm_refcount(struct anon_vma
*anon_vma
)
83 #endif /* CONFIG_KSM */
85 static inline struct anon_vma
*page_anon_vma(struct page
*page
)
87 if (((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) !=
90 return page_rmapping(page
);
93 static inline void anon_vma_lock(struct vm_area_struct
*vma
)
95 struct anon_vma
*anon_vma
= vma
->anon_vma
;
97 spin_lock(&anon_vma
->lock
);
100 static inline void anon_vma_unlock(struct vm_area_struct
*vma
)
102 struct anon_vma
*anon_vma
= vma
->anon_vma
;
104 spin_unlock(&anon_vma
->lock
);
108 * anon_vma helper functions.
110 void anon_vma_init(void); /* create anon_vma_cachep */
111 int anon_vma_prepare(struct vm_area_struct
*);
112 void unlink_anon_vmas(struct vm_area_struct
*);
113 int anon_vma_clone(struct vm_area_struct
*, struct vm_area_struct
*);
114 int anon_vma_fork(struct vm_area_struct
*, struct vm_area_struct
*);
115 void __anon_vma_link(struct vm_area_struct
*);
116 void anon_vma_free(struct anon_vma
*);
118 static inline void anon_vma_merge(struct vm_area_struct
*vma
,
119 struct vm_area_struct
*next
)
121 VM_BUG_ON(vma
->anon_vma
!= next
->anon_vma
);
122 unlink_anon_vmas(next
);
126 * rmap interfaces called when adding or removing pte of page
128 void page_move_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
129 void page_add_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
130 void page_add_new_anon_rmap(struct page
*, struct vm_area_struct
*, unsigned long);
131 void page_add_file_rmap(struct page
*);
132 void page_remove_rmap(struct page
*);
134 static inline void page_dup_rmap(struct page
*page
)
136 atomic_inc(&page
->_mapcount
);
140 * Called from mm/vmscan.c to handle paging out
142 int page_referenced(struct page
*, int is_locked
,
143 struct mem_cgroup
*cnt
, unsigned long *vm_flags
);
144 int page_referenced_one(struct page
*, struct vm_area_struct
*,
145 unsigned long address
, unsigned int *mapcount
, unsigned long *vm_flags
);
148 TTU_UNMAP
= 0, /* unmap mode */
149 TTU_MIGRATION
= 1, /* migration mode */
150 TTU_MUNLOCK
= 2, /* munlock mode */
151 TTU_ACTION_MASK
= 0xff,
153 TTU_IGNORE_MLOCK
= (1 << 8), /* ignore mlock */
154 TTU_IGNORE_ACCESS
= (1 << 9), /* don't age */
155 TTU_IGNORE_HWPOISON
= (1 << 10),/* corrupted page is recoverable */
157 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
159 int try_to_unmap(struct page
*, enum ttu_flags flags
);
160 int try_to_unmap_one(struct page
*, struct vm_area_struct
*,
161 unsigned long address
, enum ttu_flags flags
);
164 * Called from mm/filemap_xip.c to unmap empty zero page
166 pte_t
*page_check_address(struct page
*, struct mm_struct
*,
167 unsigned long, spinlock_t
**, int);
170 * Used by swapoff to help locate where page is expected in vma.
172 unsigned long page_address_in_vma(struct page
*, struct vm_area_struct
*);
175 * Cleans the PTEs of shared mappings.
176 * (and since clean PTEs should also be readonly, write protects them too)
178 * returns the number of cleaned PTEs.
180 int page_mkclean(struct page
*);
183 * called in munlock()/munmap() path to check for other vmas holding
186 int try_to_munlock(struct page
*);
189 * Called by memory-failure.c to kill processes.
191 struct anon_vma
*page_lock_anon_vma(struct page
*page
);
192 void page_unlock_anon_vma(struct anon_vma
*anon_vma
);
193 int page_mapped_in_vma(struct page
*page
, struct vm_area_struct
*vma
);
196 * Called by migrate.c to remove migration ptes, but might be used more later.
198 int rmap_walk(struct page
*page
, int (*rmap_one
)(struct page
*,
199 struct vm_area_struct
*, unsigned long, void *), void *arg
);
201 #else /* !CONFIG_MMU */
203 #define anon_vma_init() do {} while (0)
204 #define anon_vma_prepare(vma) (0)
205 #define anon_vma_link(vma) do {} while (0)
207 static inline int page_referenced(struct page
*page
, int is_locked
,
208 struct mem_cgroup
*cnt
,
209 unsigned long *vm_flags
)
215 #define try_to_unmap(page, refs) SWAP_FAIL
217 static inline int page_mkclean(struct page
*page
)
223 #endif /* CONFIG_MMU */
226 * Return values of try_to_unmap
228 #define SWAP_SUCCESS 0
233 #endif /* _LINUX_RMAP_H */