summaryrefslogtreecommitdiff
path: root/include/linux/rmap.h
blob: db2c1df4fef96acdc9715b5fb7baaa88f27c8e0f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
#ifndef _LINUX_RMAP_H
#define _LINUX_RMAP_H
/*
 * Declarations for Reverse Mapping functions in mm/rmap.c
 */

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>

/*
 * The anon_vma heads a list of private "related" vmas, to scan if
 * an anonymous page pointing to this anon_vma needs to be unmapped:
 * the vmas on the list will be related by forking, or by splitting.
 *
 * Since vmas come and go as they are split and merged (particularly
 * in mprotect), the mapping field of an anonymous page cannot point
 * directly to a vma: instead it points to an anon_vma, on whose list
 * the related vmas can be easily linked or unlinked.
 *
 * After unlinking the last vma on the list, we must garbage collect
 * the anon_vma object itself: we're guaranteed no page can be
 * pointing to this anon_vma once its vma list is empty.
 */
struct anon_vma {
	spinlock_t lock;	/* Serialize access to vma list */
	struct list_head head;	/* List of private "related" vmas */
};

#ifdef CONFIG_MMU

extern kmem_cache_t *anon_vma_cachep;

static inline struct anon_vma *anon_vma_alloc(void)
{
	return kmem_cache_alloc(anon_vma_cachep, SLAB_KERNEL);
}

static inline void anon_vma_free(struct anon_vma *anon_vma)
{
	kmem_cache_free(anon_vma_cachep, anon_vma);
}

static inline void anon_vma_lock(struct vm_area_struct *vma)
{
	struct anon_vma *anon_vma = vma->anon_vma;
	if (anon_vma)
		spin_lock(&anon_vma->lock);
}

static inline void anon_vma_unlock(struct vm_area_struct *vma)
{
	struct anon_vma *anon_vma = vma->anon_vma;
	if (anon_vma)
		spin_unlock(&anon_vma->lock);
}

/*
 * anon_vma helper functions.
 */
void anon_vma_init(void);	/* create anon_vma_cachep */
int  anon_vma_prepare(struct vm_area_struct *);
void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
void anon_vma_unlink(struct vm_area_struct *);
void anon_vma_link(struct vm_area_struct *);
void __anon_vma_link(struct vm_area_struct *);

/*
 * rmap interfaces called when adding or removing pte of page
 */
void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_file_rmap(struct page *);
void page_remove_rmap(struct page *);

/**
 * page_dup_rmap - duplicate pte mapping to a page
 * @page:	the page to add the mapping to
 *
 * For copy_page_range only: minimal extract from page_add_rmap,
 * avoiding unnecessary tests (already checked) so it's quicker.
 */
static inline void page_dup_rmap(struct page *page)
{
	atomic_inc(&page->_mapcount);
}

/*
 * Called from mm/vmscan.c to handle paging out
 */
int page_referenced(struct page *, int is_locked);
int try_to_unmap(struct page *, int ignore_refs);

/*
 * Called from mm/filemap_xip.c to unmap empty zero page
 */
pte_t *page_check_address(struct page *, struct mm_struct *,
				unsigned long, spinlock_t **);

/*
 * Used by swapoff to help locate where page is expected in vma.
 */
unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);

/*
 * Cleans the PTEs of shared mappings.
 * (and since clean PTEs should also be readonly, write protects them too)
 *
 * returns the number of cleaned PTEs.
 */
int page_mkclean(struct page *);

#else	/* !CONFIG_MMU */

#define anon_vma_init()		do {} while (0)
#define anon_vma_prepare(vma)	(0)
#define anon_vma_link(vma)	do {} while (0)

#define page_referenced(page,l) TestClearPageReferenced(page)
#define try_to_unmap(page, refs) SWAP_FAIL

static inline int page_mkclean(struct page *page)
{
	return 0;
}


#endif	/* CONFIG_MMU */

/*
 * Return values of try_to_unmap
 */
#define SWAP_SUCCESS	0
#define SWAP_AGAIN	1
#define SWAP_FAIL	2

#endif	/* _LINUX_RMAP_H */