| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef __LINUX_KSM_H |
| #define __LINUX_KSM_H |
| /* |
| * Memory merging support. |
| * |
| * This code enables dynamic sharing of identical pages found in different |
| * memory areas, even if they are not shared by fork(). |
| */ |
| |
| #include <linux/bitops.h> |
| #include <linux/mm.h> |
| #include <linux/pagemap.h> |
| #include <linux/rmap.h> |
| #include <linux/sched.h> |
| #include <linux/sched/coredump.h> |
| |
| struct stable_node; |
| struct mem_cgroup; |
| |
| #ifdef CONFIG_KSM |
| int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, int advice, unsigned long *vm_flags); |
| int __ksm_enter(struct mm_struct *mm); |
| void __ksm_exit(struct mm_struct *mm); |
| |
| static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| { |
| if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) |
| return __ksm_enter(mm); |
| return 0; |
| } |
| |
| static inline void ksm_exit(struct mm_struct *mm) |
| { |
| if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) |
| __ksm_exit(mm); |
| } |
| |
| /* |
| * When do_swap_page() first faults in from swap what used to be a KSM page, |
| * no problem, it will be assigned to this vma's anon_vma; but thereafter, |
| * it might be faulted into a different anon_vma (or perhaps to a different |
| * offset in the same anon_vma). do_swap_page() cannot do all the locking |
| * needed to reconstitute a cross-anon_vma KSM page: for now it has to make |
| * a copy, and leave remerging the pages to a later pass of ksmd. |
| * |
| * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE, |
| * but what if the vma was unmerged while the page was swapped out? |
| */ |
| struct page *ksm_might_need_to_copy(struct page *page, |
| struct vm_area_struct *vma, unsigned long address); |
| |
| void rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc); |
| void folio_migrate_ksm(struct folio *newfolio, struct folio *folio); |
| |
| #else /* !CONFIG_KSM */ |
| |
| static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| { |
| return 0; |
| } |
| |
| static inline void ksm_exit(struct mm_struct *mm) |
| { |
| } |
| |
| #ifdef CONFIG_MMU |
| static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, int advice, unsigned long *vm_flags) |
| { |
| return 0; |
| } |
| |
| static inline struct page *ksm_might_need_to_copy(struct page *page, |
| struct vm_area_struct *vma, unsigned long address) |
| { |
| return page; |
| } |
| |
| static inline void rmap_walk_ksm(struct page *page, |
| struct rmap_walk_control *rwc) |
| { |
| } |
| |
| static inline void folio_migrate_ksm(struct folio *newfolio, struct folio *old) |
| { |
| } |
| #endif /* CONFIG_MMU */ |
| #endif /* !CONFIG_KSM */ |
| |
| #endif /* __LINUX_KSM_H */ |