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> |
| 12 | #include <linux/sched.h> |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 13 | #include <linux/vmstat.h> |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 14 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 15 | struct stable_node; |
| 16 | |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 17 | #ifdef CONFIG_KSM |
| 18 | int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 19 | unsigned long end, int advice, unsigned long *vm_flags); |
| 20 | int __ksm_enter(struct mm_struct *mm); |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 21 | void __ksm_exit(struct mm_struct *mm); |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 22 | |
| 23 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| 24 | { |
| 25 | if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) |
| 26 | return __ksm_enter(mm); |
| 27 | return 0; |
| 28 | } |
| 29 | |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 30 | static inline void ksm_exit(struct mm_struct *mm) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 31 | { |
| 32 | if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 33 | __ksm_exit(mm); |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 34 | } |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 35 | |
| 36 | /* |
| 37 | * A KSM page is one of those write-protected "shared pages" or "merged pages" |
| 38 | * which KSM maps into multiple mms, wherever identical anonymous page content |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 39 | * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any |
| 40 | * anon_vma, but to that page's node of the stable tree. |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 41 | */ |
| 42 | static inline int PageKsm(struct page *page) |
| 43 | { |
Hugh Dickins | 3ca7b3c | 2009-12-14 17:58:57 -0800 | [diff] [blame] | 44 | return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == |
| 45 | (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 46 | } |
| 47 | |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 48 | static inline struct stable_node *page_stable_node(struct page *page) |
| 49 | { |
| 50 | return PageKsm(page) ? page_rmapping(page) : NULL; |
| 51 | } |
| 52 | |
| 53 | static inline void set_page_stable_node(struct page *page, |
| 54 | struct stable_node *stable_node) |
| 55 | { |
| 56 | page->mapping = (void *)stable_node + |
| 57 | (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); |
| 58 | } |
| 59 | |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 60 | static inline void page_add_ksm_rmap(struct page *page) |
| 61 | { |
Hugh Dickins | 08beca4 | 2009-12-14 17:59:21 -0800 | [diff] [blame^] | 62 | if (atomic_inc_and_test(&page->_mapcount)) |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 63 | __inc_zone_page_state(page, NR_ANON_PAGES); |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 64 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 65 | #else /* !CONFIG_KSM */ |
| 66 | |
| 67 | static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 68 | unsigned long end, int advice, unsigned long *vm_flags) |
| 69 | { |
| 70 | return 0; |
| 71 | } |
| 72 | |
| 73 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| 74 | { |
| 75 | return 0; |
| 76 | } |
| 77 | |
Andrea Arcangeli | 1c2fb7a | 2009-09-21 17:02:22 -0700 | [diff] [blame] | 78 | static inline void ksm_exit(struct mm_struct *mm) |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 79 | { |
| 80 | } |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame] | 81 | |
| 82 | static inline int PageKsm(struct page *page) |
| 83 | { |
| 84 | return 0; |
| 85 | } |
| 86 | |
| 87 | /* No stub required for page_add_ksm_rmap(page) */ |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 88 | #endif /* !CONFIG_KSM */ |
| 89 | |
| 90 | #endif |