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 #include <linux/sched/coredump.h> 16 17 struct stable_node; 18 struct mem_cgroup; 19 20 #ifdef CONFIG_KSM 21 int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 22 unsigned long end, int advice, unsigned long *vm_flags); 23 int __ksm_enter(struct mm_struct *mm); 24 void __ksm_exit(struct mm_struct *mm); 25 26 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) 27 { 28 if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) 29 return __ksm_enter(mm); 30 return 0; 31 } 32 33 static inline void ksm_exit(struct mm_struct *mm) 34 { 35 if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) 36 __ksm_exit(mm); 37 } 38 39 static inline struct stable_node *page_stable_node(struct page *page) 40 { 41 return PageKsm(page) ? page_rmapping(page) : NULL; 42 } 43 44 static inline void set_page_stable_node(struct page *page, 45 struct stable_node *stable_node) 46 { 47 page->mapping = (void *)((unsigned long)stable_node | 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 void 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 void rmap_walk_ksm(struct page *page, 98 struct rmap_walk_control *rwc) 99 { 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