1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_KSM_H 3 #define __LINUX_KSM_H 4 /* 5 * Memory merging support. 6 * 7 * This code enables dynamic sharing of identical pages found in different 8 * memory areas, even if they are not shared by fork(). 9 */ 10 11 #include <linux/bitops.h> 12 #include <linux/mm.h> 13 #include <linux/pagemap.h> 14 #include <linux/rmap.h> 15 #include <linux/sched.h> 16 #include <linux/sched/coredump.h> 17 18 #ifdef CONFIG_KSM 19 int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 20 unsigned long end, int advice, unsigned long *vm_flags); 21 22 void ksm_add_vma(struct vm_area_struct *vma); 23 int ksm_enable_merge_any(struct mm_struct *mm); 24 25 int __ksm_enter(struct mm_struct *mm); 26 void __ksm_exit(struct mm_struct *mm); 27 28 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) 29 { 30 int ret; 31 32 if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) { 33 ret = __ksm_enter(mm); 34 if (ret) 35 return ret; 36 } 37 38 if (test_bit(MMF_VM_MERGE_ANY, &oldmm->flags)) 39 set_bit(MMF_VM_MERGE_ANY, &mm->flags); 40 41 return 0; 42 } 43 44 static inline void ksm_exit(struct mm_struct *mm) 45 { 46 if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) 47 __ksm_exit(mm); 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 folio *folio, struct rmap_walk_control *rwc); 65 void folio_migrate_ksm(struct folio *newfolio, struct folio *folio); 66 67 #ifdef CONFIG_MEMORY_FAILURE 68 void collect_procs_ksm(struct page *page, struct list_head *to_kill, 69 int force_early); 70 #endif 71 72 #ifdef CONFIG_PROC_FS 73 long ksm_process_profit(struct mm_struct *); 74 #endif /* CONFIG_PROC_FS */ 75 76 #else /* !CONFIG_KSM */ 77 78 static inline void ksm_add_vma(struct vm_area_struct *vma) 79 { 80 } 81 82 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) 83 { 84 return 0; 85 } 86 87 static inline void ksm_exit(struct mm_struct *mm) 88 { 89 } 90 91 #ifdef CONFIG_MEMORY_FAILURE 92 static inline void collect_procs_ksm(struct page *page, 93 struct list_head *to_kill, int force_early) 94 { 95 } 96 #endif 97 98 #ifdef CONFIG_MMU 99 static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 100 unsigned long end, int advice, unsigned long *vm_flags) 101 { 102 return 0; 103 } 104 105 static inline struct page *ksm_might_need_to_copy(struct page *page, 106 struct vm_area_struct *vma, unsigned long address) 107 { 108 return page; 109 } 110 111 static inline void rmap_walk_ksm(struct folio *folio, 112 struct rmap_walk_control *rwc) 113 { 114 } 115 116 static inline void folio_migrate_ksm(struct folio *newfolio, struct folio *old) 117 { 118 } 119 #endif /* CONFIG_MMU */ 120 #endif /* !CONFIG_KSM */ 121 122 #endif /* __LINUX_KSM_H */ 123