Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 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> |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 12 | #include <linux/pagemap.h> |
| 13 | #include <linux/rmap.h> |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 14 | #include <linux/sched.h> |
| 15 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 16 | struct stable_node; |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 17 | struct mem_cgroup; |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 18 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 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); |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 23 | void __ksm_exit(struct mm_struct *mm); |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 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 | |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 32 | static inline void ksm_exit(struct mm_struct *mm) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 33 | { |
| 34 | if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 35 | __ksm_exit(mm); |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 36 | } |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 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 |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 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. |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 43 | */ |
| 44 | static inline int PageKsm(struct page *page) |
| 45 | { |
Hugh Dickins | 3ca7b3c | 2009-12-14 17:58:57 -0800 | [diff] [blame] | 46 | return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == |
| 47 | (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 48 | } |
| 49 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame] | 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 | |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 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) |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 77 | { |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 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); |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 86 | } |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 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); |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 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); |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 94 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 95 | #else /* !CONFIG_KSM */ |
| 96 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 97 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| 98 | { |
| 99 | return 0; |
| 100 | } |
| 101 | |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 102 | static inline void ksm_exit(struct mm_struct *mm) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 103 | { |
| 104 | } |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 105 | |
| 106 | static inline int PageKsm(struct page *page) |
| 107 | { |
| 108 | return 0; |
| 109 | } |
| 110 | |
Hugh Dickins | f42647a | 2009-12-16 08:56:57 +0000 | [diff] [blame^] | 111 | #ifdef CONFIG_MMU |
| 112 | static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 113 | unsigned long end, int advice, unsigned long *vm_flags) |
| 114 | { |
| 115 | return 0; |
| 116 | } |
| 117 | |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 118 | static inline struct page *ksm_might_need_to_copy(struct page *page, |
| 119 | struct vm_area_struct *vma, unsigned long address) |
| 120 | { |
| 121 | return page; |
| 122 | } |
| 123 | |
| 124 | static inline int page_referenced_ksm(struct page *page, |
| 125 | struct mem_cgroup *memcg, unsigned long *vm_flags) |
| 126 | { |
| 127 | return 0; |
| 128 | } |
| 129 | |
| 130 | static inline int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) |
| 131 | { |
| 132 | return 0; |
| 133 | } |
Hugh Dickins | e9995ef | 2009-12-14 17:59:31 -0800 | [diff] [blame] | 134 | |
| 135 | static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page*, |
| 136 | struct vm_area_struct *, unsigned long, void *), void *arg) |
| 137 | { |
| 138 | return 0; |
| 139 | } |
| 140 | |
| 141 | static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage) |
| 142 | { |
| 143 | } |
Hugh Dickins | f42647a | 2009-12-16 08:56:57 +0000 | [diff] [blame^] | 144 | #endif /* CONFIG_MMU */ |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 145 | #endif /* !CONFIG_KSM */ |
| 146 | |
Hugh Dickins | 5ad6468 | 2009-12-14 17:59:24 -0800 | [diff] [blame] | 147 | #endif /* __LINUX_KSM_H */ |