Linux kernel mirror (for testing)
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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#ifdef CONFIG_KSM
30 atomic_t ksm_refcount;
31#endif
32 /*
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).
39 */
40 struct list_head head; /* Chain of private "related" vmas */
41};
42
43/*
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.
48 *
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.
55 */
56struct 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 */
61};
62
63#ifdef CONFIG_MMU
64#ifdef CONFIG_KSM
65static inline void ksm_refcount_init(struct anon_vma *anon_vma)
66{
67 atomic_set(&anon_vma->ksm_refcount, 0);
68}
69
70static inline int ksm_refcount(struct anon_vma *anon_vma)
71{
72 return atomic_read(&anon_vma->ksm_refcount);
73}
74#else
75static inline void ksm_refcount_init(struct anon_vma *anon_vma)
76{
77}
78
79static inline int ksm_refcount(struct anon_vma *anon_vma)
80{
81 return 0;
82}
83#endif /* CONFIG_KSM */
84
85static inline struct anon_vma *page_anon_vma(struct page *page)
86{
87 if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
88 PAGE_MAPPING_ANON)
89 return NULL;
90 return page_rmapping(page);
91}
92
93static inline void anon_vma_lock(struct vm_area_struct *vma)
94{
95 struct anon_vma *anon_vma = vma->anon_vma;
96 if (anon_vma)
97 spin_lock(&anon_vma->lock);
98}
99
100static inline void anon_vma_unlock(struct vm_area_struct *vma)
101{
102 struct anon_vma *anon_vma = vma->anon_vma;
103 if (anon_vma)
104 spin_unlock(&anon_vma->lock);
105}
106
107/*
108 * anon_vma helper functions.
109 */
110void anon_vma_init(void); /* create anon_vma_cachep */
111int anon_vma_prepare(struct vm_area_struct *);
112void unlink_anon_vmas(struct vm_area_struct *);
113int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
114int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
115void __anon_vma_link(struct vm_area_struct *);
116void anon_vma_free(struct anon_vma *);
117
118static inline void anon_vma_merge(struct vm_area_struct *vma,
119 struct vm_area_struct *next)
120{
121 VM_BUG_ON(vma->anon_vma != next->anon_vma);
122 unlink_anon_vmas(next);
123}
124
125/*
126 * rmap interfaces called when adding or removing pte of page
127 */
128void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
129void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
130void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
131void page_add_file_rmap(struct page *);
132void page_remove_rmap(struct page *);
133
134static inline void page_dup_rmap(struct page *page)
135{
136 atomic_inc(&page->_mapcount);
137}
138
139/*
140 * Called from mm/vmscan.c to handle paging out
141 */
142int page_referenced(struct page *, int is_locked,
143 struct mem_cgroup *cnt, unsigned long *vm_flags);
144int page_referenced_one(struct page *, struct vm_area_struct *,
145 unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
146
147enum ttu_flags {
148 TTU_UNMAP = 0, /* unmap mode */
149 TTU_MIGRATION = 1, /* migration mode */
150 TTU_MUNLOCK = 2, /* munlock mode */
151 TTU_ACTION_MASK = 0xff,
152
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 */
156};
157#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
158
159int try_to_unmap(struct page *, enum ttu_flags flags);
160int try_to_unmap_one(struct page *, struct vm_area_struct *,
161 unsigned long address, enum ttu_flags flags);
162
163/*
164 * Called from mm/filemap_xip.c to unmap empty zero page
165 */
166pte_t *page_check_address(struct page *, struct mm_struct *,
167 unsigned long, spinlock_t **, int);
168
169/*
170 * Used by swapoff to help locate where page is expected in vma.
171 */
172unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
173
174/*
175 * Cleans the PTEs of shared mappings.
176 * (and since clean PTEs should also be readonly, write protects them too)
177 *
178 * returns the number of cleaned PTEs.
179 */
180int page_mkclean(struct page *);
181
182/*
183 * called in munlock()/munmap() path to check for other vmas holding
184 * the page mlocked.
185 */
186int try_to_munlock(struct page *);
187
188/*
189 * Called by memory-failure.c to kill processes.
190 */
191struct anon_vma *page_lock_anon_vma(struct page *page);
192void page_unlock_anon_vma(struct anon_vma *anon_vma);
193int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
194
195/*
196 * Called by migrate.c to remove migration ptes, but might be used more later.
197 */
198int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
199 struct vm_area_struct *, unsigned long, void *), void *arg);
200
201#else /* !CONFIG_MMU */
202
203#define anon_vma_init() do {} while (0)
204#define anon_vma_prepare(vma) (0)
205#define anon_vma_link(vma) do {} while (0)
206
207static inline int page_referenced(struct page *page, int is_locked,
208 struct mem_cgroup *cnt,
209 unsigned long *vm_flags)
210{
211 *vm_flags = 0;
212 return 0;
213}
214
215#define try_to_unmap(page, refs) SWAP_FAIL
216
217static inline int page_mkclean(struct page *page)
218{
219 return 0;
220}
221
222
223#endif /* CONFIG_MMU */
224
225/*
226 * Return values of try_to_unmap
227 */
228#define SWAP_SUCCESS 0
229#define SWAP_AGAIN 1
230#define SWAP_FAIL 2
231#define SWAP_MLOCK 3
232
233#endif /* _LINUX_RMAP_H */