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f8af4da3 HD |
1 | #ifndef __LINUX_KSM_H |
2 | #define __LINUX_KSM_H | |
3 | /* | |
4 | * Memory merging support. | |
5 | * | |
6 | * This code enables dynamic sharing of identical pages found in different | |
7 | * memory areas, even if they are not shared by fork(). | |
8 | */ | |
9 | ||
10 | #include <linux/bitops.h> | |
11 | #include <linux/mm.h> | |
5ad64688 HD |
12 | #include <linux/pagemap.h> |
13 | #include <linux/rmap.h> | |
f8af4da3 HD |
14 | #include <linux/sched.h> |
15 | ||
08beca44 | 16 | struct stable_node; |
5ad64688 | 17 | struct mem_cgroup; |
08beca44 | 18 | |
f8af4da3 HD |
19 | #ifdef CONFIG_KSM |
20 | int ksm_madvise(struct vm_area_struct *vma, unsigned long start, | |
21 | unsigned long end, int advice, unsigned long *vm_flags); | |
22 | int __ksm_enter(struct mm_struct *mm); | |
1c2fb7a4 | 23 | void __ksm_exit(struct mm_struct *mm); |
f8af4da3 HD |
24 | |
25 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) | |
26 | { | |
27 | if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) | |
28 | return __ksm_enter(mm); | |
29 | return 0; | |
30 | } | |
31 | ||
1c2fb7a4 | 32 | static inline void ksm_exit(struct mm_struct *mm) |
f8af4da3 HD |
33 | { |
34 | if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) | |
1c2fb7a4 | 35 | __ksm_exit(mm); |
f8af4da3 | 36 | } |
9a840895 HD |
37 | |
38 | /* | |
39 | * A KSM page is one of those write-protected "shared pages" or "merged pages" | |
40 | * which KSM maps into multiple mms, wherever identical anonymous page content | |
08beca44 HD |
41 | * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any |
42 | * anon_vma, but to that page's node of the stable tree. | |
9a840895 HD |
43 | */ |
44 | static inline int PageKsm(struct page *page) | |
45 | { | |
3ca7b3c5 HD |
46 | return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == |
47 | (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); | |
9a840895 HD |
48 | } |
49 | ||
08beca44 HD |
50 | static inline struct stable_node *page_stable_node(struct page *page) |
51 | { | |
52 | return PageKsm(page) ? page_rmapping(page) : NULL; | |
53 | } | |
54 | ||
55 | static inline void set_page_stable_node(struct page *page, | |
56 | struct stable_node *stable_node) | |
57 | { | |
58 | page->mapping = (void *)stable_node + | |
59 | (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); | |
60 | } | |
61 | ||
5ad64688 HD |
62 | /* |
63 | * When do_swap_page() first faults in from swap what used to be a KSM page, | |
64 | * no problem, it will be assigned to this vma's anon_vma; but thereafter, | |
65 | * it might be faulted into a different anon_vma (or perhaps to a different | |
66 | * offset in the same anon_vma). do_swap_page() cannot do all the locking | |
67 | * needed to reconstitute a cross-anon_vma KSM page: for now it has to make | |
68 | * a copy, and leave remerging the pages to a later pass of ksmd. | |
69 | * | |
70 | * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE, | |
71 | * but what if the vma was unmerged while the page was swapped out? | |
72 | */ | |
73 | struct page *ksm_does_need_to_copy(struct page *page, | |
74 | struct vm_area_struct *vma, unsigned long address); | |
75 | static inline struct page *ksm_might_need_to_copy(struct page *page, | |
76 | struct vm_area_struct *vma, unsigned long address) | |
9a840895 | 77 | { |
5ad64688 HD |
78 | struct anon_vma *anon_vma = page_anon_vma(page); |
79 | ||
80 | if (!anon_vma || | |
81 | (anon_vma == vma->anon_vma && | |
82 | page->index == linear_page_index(vma, address))) | |
83 | return page; | |
84 | ||
85 | return ksm_does_need_to_copy(page, vma, address); | |
9a840895 | 86 | } |
5ad64688 HD |
87 | |
88 | int page_referenced_ksm(struct page *page, | |
89 | struct mem_cgroup *memcg, unsigned long *vm_flags); | |
90 | int try_to_unmap_ksm(struct page *page, enum ttu_flags flags); | |
e9995ef9 HD |
91 | int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *, |
92 | struct vm_area_struct *, unsigned long, void *), void *arg); | |
93 | void ksm_migrate_page(struct page *newpage, struct page *oldpage); | |
5ad64688 | 94 | |
f8af4da3 HD |
95 | #else /* !CONFIG_KSM */ |
96 | ||
97 | static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, | |
98 | unsigned long end, int advice, unsigned long *vm_flags) | |
99 | { | |
100 | return 0; | |
101 | } | |
102 | ||
103 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) | |
104 | { | |
105 | return 0; | |
106 | } | |
107 | ||
1c2fb7a4 | 108 | static inline void ksm_exit(struct mm_struct *mm) |
f8af4da3 HD |
109 | { |
110 | } | |
9a840895 HD |
111 | |
112 | static inline int PageKsm(struct page *page) | |
113 | { | |
114 | return 0; | |
115 | } | |
116 | ||
5ad64688 HD |
117 | static inline struct page *ksm_might_need_to_copy(struct page *page, |
118 | struct vm_area_struct *vma, unsigned long address) | |
119 | { | |
120 | return page; | |
121 | } | |
122 | ||
123 | static inline int page_referenced_ksm(struct page *page, | |
124 | struct mem_cgroup *memcg, unsigned long *vm_flags) | |
125 | { | |
126 | return 0; | |
127 | } | |
128 | ||
129 | static inline int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) | |
130 | { | |
131 | return 0; | |
132 | } | |
e9995ef9 HD |
133 | |
134 | static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page*, | |
135 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
136 | { | |
137 | return 0; | |
138 | } | |
139 | ||
140 | static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage) | |
141 | { | |
142 | } | |
f8af4da3 HD |
143 | #endif /* !CONFIG_KSM */ |
144 | ||
5ad64688 | 145 | #endif /* __LINUX_KSM_H */ |