Commit | Line | Data |
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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 | */ | |
cbf86cfe HD |
73 | struct page *ksm_might_need_to_copy(struct page *page, |
74 | struct vm_area_struct *vma, unsigned long address); | |
5ad64688 | 75 | |
051ac83a | 76 | int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc); |
e9995ef9 | 77 | void ksm_migrate_page(struct page *newpage, struct page *oldpage); |
5ad64688 | 78 | |
f8af4da3 HD |
79 | #else /* !CONFIG_KSM */ |
80 | ||
f8af4da3 HD |
81 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
82 | { | |
83 | return 0; | |
84 | } | |
85 | ||
1c2fb7a4 | 86 | static inline void ksm_exit(struct mm_struct *mm) |
f8af4da3 HD |
87 | { |
88 | } | |
9a840895 HD |
89 | |
90 | static inline int PageKsm(struct page *page) | |
91 | { | |
92 | return 0; | |
93 | } | |
94 | ||
f42647ac HD |
95 | #ifdef CONFIG_MMU |
96 | static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, | |
97 | unsigned long end, int advice, unsigned long *vm_flags) | |
98 | { | |
99 | return 0; | |
100 | } | |
101 | ||
cbf86cfe | 102 | static inline struct page *ksm_might_need_to_copy(struct page *page, |
5ad64688 HD |
103 | struct vm_area_struct *vma, unsigned long address) |
104 | { | |
cbf86cfe | 105 | return page; |
5ad64688 HD |
106 | } |
107 | ||
108 | static inline int page_referenced_ksm(struct page *page, | |
109 | struct mem_cgroup *memcg, unsigned long *vm_flags) | |
110 | { | |
111 | return 0; | |
112 | } | |
113 | ||
051ac83a JK |
114 | static inline int rmap_walk_ksm(struct page *page, |
115 | struct rmap_walk_control *rwc) | |
e9995ef9 HD |
116 | { |
117 | return 0; | |
118 | } | |
119 | ||
120 | static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage) | |
121 | { | |
122 | } | |
f42647ac | 123 | #endif /* CONFIG_MMU */ |
f8af4da3 HD |
124 | #endif /* !CONFIG_KSM */ |
125 | ||
5ad64688 | 126 | #endif /* __LINUX_KSM_H */ |