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