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/pagemap.h> 13 #include <linux/rmap.h> 14 #include <linux/sched.h> 15 16 struct stable_node; 17 struct mem_cgroup; 18 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); 23 void __ksm_exit(struct mm_struct *mm); 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 32 static inline void ksm_exit(struct mm_struct *mm) 33 { 34 if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) 35 __ksm_exit(mm); 36 } 37 38 static inline struct stable_node *page_stable_node(struct page *page) 39 { 40 return PageKsm(page) ? page_rmapping(page) : NULL; 41 } 42 43 static inline void set_page_stable_node(struct page *page, 44 struct stable_node *stable_node) 45 { 46 page->mapping = (void *)stable_node + 47 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); 48 } 49 50 /* 51 * When do_swap_page() first faults in from swap what used to be a KSM page, 52 * no problem, it will be assigned to this vma's anon_vma; but thereafter, 53 * it might be faulted into a different anon_vma (or perhaps to a different 54 * offset in the same anon_vma). do_swap_page() cannot do all the locking 55 * needed to reconstitute a cross-anon_vma KSM page: for now it has to make 56 * a copy, and leave remerging the pages to a later pass of ksmd. 57 * 58 * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE, 59 * but what if the vma was unmerged while the page was swapped out? 60 */ 61 struct page *ksm_might_need_to_copy(struct page *page, 62 struct vm_area_struct *vma, unsigned long address); 63 64 int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc); 65 void ksm_migrate_page(struct page *newpage, struct page *oldpage); 66 67 #else /* !CONFIG_KSM */ 68 69 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) 70 { 71 return 0; 72 } 73 74 static inline void ksm_exit(struct mm_struct *mm) 75 { 76 } 77 78 #ifdef CONFIG_MMU 79 static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 80 unsigned long end, int advice, unsigned long *vm_flags) 81 { 82 return 0; 83 } 84 85 static inline struct page *ksm_might_need_to_copy(struct page *page, 86 struct vm_area_struct *vma, unsigned long address) 87 { 88 return page; 89 } 90 91 static inline int page_referenced_ksm(struct page *page, 92 struct mem_cgroup *memcg, unsigned long *vm_flags) 93 { 94 return 0; 95 } 96 97 static inline int rmap_walk_ksm(struct page *page, 98 struct rmap_walk_control *rwc) 99 { 100 return 0; 101 } 102 103 static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage) 104 { 105 } 106 #endif /* CONFIG_MMU */ 107 #endif /* !CONFIG_KSM */ 108 109 #endif /* __LINUX_KSM_H */ 110