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 */
27 struct anon_vma {
28 spinlock_t lock; /* Serialize access to vma list */
29 /*
30 * NOTE: the LSB of the head.next is set by
31 * mm_take_all_locks() _after_ taking the above lock. So the
32 * head must only be read/written after taking the above lock
33 * to be sure to see a valid next pointer. The LSB bit itself
34 * is serialized by a system wide lock only visible to
35 * mm_take_all_locks() (mm_all_locks_mutex).
36 */
37 struct list_head head; /* List of private "related" vmas */
38 };
39
40 #ifdef CONFIG_MMU
41
anon_vma_lock(struct vm_area_struct * vma)42 static inline void anon_vma_lock(struct vm_area_struct *vma)
43 {
44 struct anon_vma *anon_vma = vma->anon_vma;
45 if (anon_vma)
46 spin_lock(&anon_vma->lock);
47 }
48
anon_vma_unlock(struct vm_area_struct * vma)49 static inline void anon_vma_unlock(struct vm_area_struct *vma)
50 {
51 struct anon_vma *anon_vma = vma->anon_vma;
52 if (anon_vma)
53 spin_unlock(&anon_vma->lock);
54 }
55
56 /*
57 * anon_vma helper functions.
58 */
59 void anon_vma_init(void); /* create anon_vma_cachep */
60 int anon_vma_prepare(struct vm_area_struct *);
61 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
62 void anon_vma_unlink(struct vm_area_struct *);
63 void anon_vma_link(struct vm_area_struct *);
64 void __anon_vma_link(struct vm_area_struct *);
65
66 /*
67 * rmap interfaces called when adding or removing pte of page
68 */
69 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
70 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
71 void page_add_file_rmap(struct page *);
72 void page_remove_rmap(struct page *);
73
74 #ifdef CONFIG_DEBUG_VM
75 void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address);
76 #else
page_dup_rmap(struct page * page,struct vm_area_struct * vma,unsigned long address)77 static inline void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
78 {
79 atomic_inc(&page->_mapcount);
80 }
81 #endif
82
83 /*
84 * Called from mm/vmscan.c to handle paging out
85 */
86 int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt);
87 int try_to_unmap(struct page *, int ignore_refs);
88
89 /*
90 * Called from mm/filemap_xip.c to unmap empty zero page
91 */
92 pte_t *page_check_address(struct page *, struct mm_struct *,
93 unsigned long, spinlock_t **, int);
94
95 /*
96 * Used by swapoff to help locate where page is expected in vma.
97 */
98 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
99
100 /*
101 * Cleans the PTEs of shared mappings.
102 * (and since clean PTEs should also be readonly, write protects them too)
103 *
104 * returns the number of cleaned PTEs.
105 */
106 int page_mkclean(struct page *);
107
108 #ifdef CONFIG_UNEVICTABLE_LRU
109 /*
110 * called in munlock()/munmap() path to check for other vmas holding
111 * the page mlocked.
112 */
113 int try_to_munlock(struct page *);
114 #else
try_to_munlock(struct page * page)115 static inline int try_to_munlock(struct page *page)
116 {
117 return 0; /* a.k.a. SWAP_SUCCESS */
118 }
119 #endif
120
121 #else /* !CONFIG_MMU */
122
123 #define anon_vma_init() do {} while (0)
124 #define anon_vma_prepare(vma) (0)
125 #define anon_vma_link(vma) do {} while (0)
126
127 #define page_referenced(page,l,cnt) TestClearPageReferenced(page)
128 #define try_to_unmap(page, refs) SWAP_FAIL
129
page_mkclean(struct page * page)130 static inline int page_mkclean(struct page *page)
131 {
132 return 0;
133 }
134
135
136 #endif /* CONFIG_MMU */
137
138 /*
139 * Return values of try_to_unmap
140 */
141 #define SWAP_SUCCESS 0
142 #define SWAP_AGAIN 1
143 #define SWAP_FAIL 2
144 #define SWAP_MLOCK 3
145
146 #endif /* _LINUX_RMAP_H */
147