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 | |
| 15 | #ifdef CONFIG_KSM |
| 16 | int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 17 | unsigned long end, int advice, unsigned long *vm_flags); |
| 18 | int __ksm_enter(struct mm_struct *mm); |
| 19 | void __ksm_exit(struct mm_struct *mm); |
| 20 | |
| 21 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| 22 | { |
| 23 | if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) |
| 24 | return __ksm_enter(mm); |
| 25 | return 0; |
| 26 | } |
| 27 | |
| 28 | static inline void ksm_exit(struct mm_struct *mm) |
| 29 | { |
| 30 | if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) |
| 31 | __ksm_exit(mm); |
| 32 | } |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame^] | 33 | |
| 34 | /* |
| 35 | * A KSM page is one of those write-protected "shared pages" or "merged pages" |
| 36 | * which KSM maps into multiple mms, wherever identical anonymous page content |
| 37 | * is found in VM_MERGEABLE vmas. It's a PageAnon page, with NULL anon_vma. |
| 38 | */ |
| 39 | static inline int PageKsm(struct page *page) |
| 40 | { |
| 41 | return ((unsigned long)page->mapping == PAGE_MAPPING_ANON); |
| 42 | } |
| 43 | |
| 44 | /* |
| 45 | * But we have to avoid the checking which page_add_anon_rmap() performs. |
| 46 | */ |
| 47 | static inline void page_add_ksm_rmap(struct page *page) |
| 48 | { |
| 49 | if (atomic_inc_and_test(&page->_mapcount)) { |
| 50 | page->mapping = (void *) PAGE_MAPPING_ANON; |
| 51 | __inc_zone_page_state(page, NR_ANON_PAGES); |
| 52 | } |
| 53 | } |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 54 | #else /* !CONFIG_KSM */ |
| 55 | |
| 56 | static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| 57 | unsigned long end, int advice, unsigned long *vm_flags) |
| 58 | { |
| 59 | return 0; |
| 60 | } |
| 61 | |
| 62 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| 63 | { |
| 64 | return 0; |
| 65 | } |
| 66 | |
| 67 | static inline void ksm_exit(struct mm_struct *mm) |
| 68 | { |
| 69 | } |
Hugh Dickins | 9a84089 | 2009-09-21 17:02:01 -0700 | [diff] [blame^] | 70 | |
| 71 | static inline int PageKsm(struct page *page) |
| 72 | { |
| 73 | return 0; |
| 74 | } |
| 75 | |
| 76 | /* No stub required for page_add_ksm_rmap(page) */ |
Hugh Dickins | f8af4da | 2009-09-21 17:01:57 -0700 | [diff] [blame] | 77 | #endif /* !CONFIG_KSM */ |
| 78 | |
| 79 | #endif |