Linux kernel mirror (for testing)
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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
19int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
20 unsigned long end, int advice, unsigned long *vm_flags);
21
22void ksm_add_vma(struct vm_area_struct *vma);
23int ksm_enable_merge_any(struct mm_struct *mm);
24int ksm_disable_merge_any(struct mm_struct *mm);
25int ksm_disable(struct mm_struct *mm);
26
27int __ksm_enter(struct mm_struct *mm);
28void __ksm_exit(struct mm_struct *mm);
29
30static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
31{
32 int ret;
33
34 if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) {
35 ret = __ksm_enter(mm);
36 if (ret)
37 return ret;
38 }
39
40 if (test_bit(MMF_VM_MERGE_ANY, &oldmm->flags))
41 set_bit(MMF_VM_MERGE_ANY, &mm->flags);
42
43 return 0;
44}
45
46static inline void ksm_exit(struct mm_struct *mm)
47{
48 if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
49 __ksm_exit(mm);
50}
51
52/*
53 * When do_swap_page() first faults in from swap what used to be a KSM page,
54 * no problem, it will be assigned to this vma's anon_vma; but thereafter,
55 * it might be faulted into a different anon_vma (or perhaps to a different
56 * offset in the same anon_vma). do_swap_page() cannot do all the locking
57 * needed to reconstitute a cross-anon_vma KSM page: for now it has to make
58 * a copy, and leave remerging the pages to a later pass of ksmd.
59 *
60 * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
61 * but what if the vma was unmerged while the page was swapped out?
62 */
63struct page *ksm_might_need_to_copy(struct page *page,
64 struct vm_area_struct *vma, unsigned long address);
65
66void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc);
67void folio_migrate_ksm(struct folio *newfolio, struct folio *folio);
68
69#ifdef CONFIG_MEMORY_FAILURE
70void collect_procs_ksm(struct page *page, struct list_head *to_kill,
71 int force_early);
72#endif
73
74#ifdef CONFIG_PROC_FS
75long ksm_process_profit(struct mm_struct *);
76#endif /* CONFIG_PROC_FS */
77
78#else /* !CONFIG_KSM */
79
80static inline void ksm_add_vma(struct vm_area_struct *vma)
81{
82}
83
84static inline int ksm_disable(struct mm_struct *mm)
85{
86 return 0;
87}
88
89static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
90{
91 return 0;
92}
93
94static inline void ksm_exit(struct mm_struct *mm)
95{
96}
97
98#ifdef CONFIG_MEMORY_FAILURE
99static inline void collect_procs_ksm(struct page *page,
100 struct list_head *to_kill, int force_early)
101{
102}
103#endif
104
105#ifdef CONFIG_MMU
106static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
107 unsigned long end, int advice, unsigned long *vm_flags)
108{
109 return 0;
110}
111
112static inline struct page *ksm_might_need_to_copy(struct page *page,
113 struct vm_area_struct *vma, unsigned long address)
114{
115 return page;
116}
117
118static inline void rmap_walk_ksm(struct folio *folio,
119 struct rmap_walk_control *rwc)
120{
121}
122
123static inline void folio_migrate_ksm(struct folio *newfolio, struct folio *old)
124{
125}
126#endif /* CONFIG_MMU */
127#endif /* !CONFIG_KSM */
128
129#endif /* __LINUX_KSM_H */