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