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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - include/linux/rmap.h
4 * Declarations for Reverse Mapping functions in mm/rmap.c
7 #include <linux/list.h>
8 #include <linux/slab.h>
10 #include <linux/rwsem.h>
11 #include <linux/memcontrol.h>
12 #include <linux/highmem.h>
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.
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.
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.
29 struct anon_vma
*root
; /* Root of this anon_vma tree */
30 struct rw_semaphore rwsem
; /* W: modification, R: walking the list */
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
41 * Count of child anon_vmas and VMAs which points to this anon_vma.
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.
48 struct anon_vma
*parent
; /* Parent of this anon_vma */
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).
58 struct rb_root rb_root
; /* Interval tree of private "related" vmas */
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.
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.
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
;
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 */
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:
103 static inline void get_anon_vma(struct anon_vma
*anon_vma
)
105 atomic_inc(&anon_vma
->refcount
);
108 void __put_anon_vma(struct anon_vma
*anon_vma
);
110 static inline void put_anon_vma(struct anon_vma
*anon_vma
)
112 if (atomic_dec_and_test(&anon_vma
->refcount
))
113 __put_anon_vma(anon_vma
);
116 static inline void anon_vma_lock_write(struct anon_vma
*anon_vma
)
118 down_write(&anon_vma
->root
->rwsem
);
121 static inline void anon_vma_unlock_write(struct anon_vma
*anon_vma
)
123 up_write(&anon_vma
->root
->rwsem
);
126 static inline void anon_vma_lock_read(struct anon_vma
*anon_vma
)
128 down_read(&anon_vma
->root
->rwsem
);
131 static inline void anon_vma_unlock_read(struct anon_vma
*anon_vma
)
133 up_read(&anon_vma
->root
->rwsem
);
138 * anon_vma helper functions.
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
*);
146 static inline int anon_vma_prepare(struct vm_area_struct
*vma
)
148 if (likely(vma
->anon_vma
))
151 return __anon_vma_prepare(vma
);
154 static inline void anon_vma_merge(struct vm_area_struct
*vma
,
155 struct vm_area_struct
*next
)
157 VM_BUG_ON_VMA(vma
->anon_vma
!= next
->anon_vma
, vma
);
158 unlink_anon_vmas(next
);
161 struct anon_vma
*page_get_anon_vma(struct page
*page
);
163 /* bitflags for do_page_add_anon_rmap() */
164 #define RMAP_EXCLUSIVE 0x01
165 #define RMAP_COMPOUND 0x02
168 * rmap interfaces called when adding or removing pte of page
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
*,
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);
180 void hugepage_add_anon_rmap(struct page
*, struct vm_area_struct
*,
182 void hugepage_add_new_anon_rmap(struct page
*, struct vm_area_struct
*,
185 static inline void page_dup_rmap(struct page
*page
, bool compound
)
187 atomic_inc(compound
? compound_mapcount_ptr(page
) : &page
->_mapcount
);
191 * Called from mm/vmscan.c to handle paging out
193 int page_referenced(struct page
*, int is_locked
,
194 struct mem_cgroup
*memcg
, unsigned long *vm_flags
);
196 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
198 int try_to_unmap(struct page
*, enum ttu_flags flags
);
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)
205 struct page_vma_mapped_walk
{
207 struct vm_area_struct
*vma
;
208 unsigned long address
;
215 static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk
*pvmw
)
218 pte_unmap(pvmw
->pte
);
220 spin_unlock(pvmw
->ptl
);
223 bool page_vma_mapped_walk(struct page_vma_mapped_walk
*pvmw
);
226 * Used by swapoff to help locate where page is expected in vma.
228 unsigned long page_address_in_vma(struct page
*, struct vm_area_struct
*);
231 * Cleans the PTEs of shared mappings.
232 * (and since clean PTEs should also be readonly, write protects them too)
234 * returns the number of cleaned PTEs.
236 int page_mkclean(struct page
*);
239 * called in munlock()/munmap() path to check for other vmas holding
242 int try_to_munlock(struct page
*);
244 void remove_migration_ptes(struct page
*old
, struct page
*new, bool locked
);
247 * Called by memory-failure.c to kill processes.
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
);
254 * rmap_walk_control: To control rmap traversing for specific needs
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
262 struct rmap_walk_control
{
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
);
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
);
274 #else /* !CONFIG_MMU */
276 #define anon_vma_init() do {} while (0)
277 #define anon_vma_prepare(vma) (0)
278 #define anon_vma_link(vma) do {} while (0)
280 static inline int page_referenced(struct page
*page
, int is_locked
,
281 struct mem_cgroup
*memcg
,
282 unsigned long *vm_flags
)
288 #define try_to_unmap(page, refs) SWAP_FAIL
290 static inline int page_mkclean(struct page
*page
)
296 #endif /* CONFIG_MMU */
299 * Return values of try_to_unmap
301 #define SWAP_SUCCESS 0
305 #define SWAP_LZFREE 4
307 #endif /* _LINUX_RMAP_H */