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 | struct stable_node; |
19 | struct mem_cgroup; |
20 | |
21 | #ifdef CONFIG_KSM |
22 | int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
23 | unsigned long end, int advice, unsigned long *vm_flags); |
24 | int __ksm_enter(struct mm_struct *mm); |
25 | void __ksm_exit(struct mm_struct *mm); |
26 | |
27 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
28 | { |
29 | if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) |
30 | return __ksm_enter(mm); |
31 | return 0; |
32 | } |
33 | |
34 | static inline void ksm_exit(struct mm_struct *mm) |
35 | { |
36 | if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) |
37 | __ksm_exit(mm); |
38 | } |
39 | |
40 | /* |
41 | * When do_swap_page() first faults in from swap what used to be a KSM page, |
42 | * no problem, it will be assigned to this vma's anon_vma; but thereafter, |
43 | * it might be faulted into a different anon_vma (or perhaps to a different |
44 | * offset in the same anon_vma). do_swap_page() cannot do all the locking |
45 | * needed to reconstitute a cross-anon_vma KSM page: for now it has to make |
46 | * a copy, and leave remerging the pages to a later pass of ksmd. |
47 | * |
48 | * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE, |
49 | * but what if the vma was unmerged while the page was swapped out? |
50 | */ |
51 | struct page *ksm_might_need_to_copy(struct page *page, |
52 | struct vm_area_struct *vma, unsigned long address); |
53 | |
54 | void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc); |
55 | void folio_migrate_ksm(struct folio *newfolio, struct folio *folio); |
56 | |
57 | #else /* !CONFIG_KSM */ |
58 | |
59 | static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
60 | { |
61 | return 0; |
62 | } |
63 | |
64 | static inline void ksm_exit(struct mm_struct *mm) |
65 | { |
66 | } |
67 | |
68 | #ifdef CONFIG_MMU |
69 | static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
70 | unsigned long end, int advice, unsigned long *vm_flags) |
71 | { |
72 | return 0; |
73 | } |
74 | |
75 | static inline struct page *ksm_might_need_to_copy(struct page *page, |
76 | struct vm_area_struct *vma, unsigned long address) |
77 | { |
78 | return page; |
79 | } |
80 | |
81 | static inline void rmap_walk_ksm(struct folio *folio, |
82 | struct rmap_walk_control *rwc) |
83 | { |
84 | } |
85 | |
86 | static inline void folio_migrate_ksm(struct folio *newfolio, struct folio *old) |
87 | { |
88 | } |
89 | #endif /* CONFIG_MMU */ |
90 | #endif /* !CONFIG_KSM */ |
91 | |
92 | #endif /* __LINUX_KSM_H */ |
93 | |