127 lines
3.3 KiB
C
127 lines
3.3 KiB
C
#ifndef __LINUX_KSM_H
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#define __LINUX_KSM_H
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/*
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* Memory merging support.
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*
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* This code enables dynamic sharing of identical pages found in different
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* memory areas, even if they are not shared by fork().
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*/
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#include <linux/bitops.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/rmap.h>
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#include <linux/sched.h>
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struct stable_node;
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struct mem_cgroup;
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#ifdef CONFIG_KSM
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int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
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unsigned long end, int advice, unsigned long *vm_flags);
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int __ksm_enter(struct mm_struct *mm);
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void __ksm_exit(struct mm_struct *mm);
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static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
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return __ksm_enter(mm);
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return 0;
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}
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static inline void ksm_exit(struct mm_struct *mm)
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{
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if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
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__ksm_exit(mm);
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}
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/*
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* A KSM page is one of those write-protected "shared pages" or "merged pages"
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* which KSM maps into multiple mms, wherever identical anonymous page content
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* is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
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* anon_vma, but to that page's node of the stable tree.
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*/
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static inline int PageKsm(struct page *page)
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{
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return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
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(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
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}
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static inline struct stable_node *page_stable_node(struct page *page)
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{
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return PageKsm(page) ? page_rmapping(page) : NULL;
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}
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static inline void set_page_stable_node(struct page *page,
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struct stable_node *stable_node)
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{
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page->mapping = (void *)stable_node +
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(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
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}
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/*
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* When do_swap_page() first faults in from swap what used to be a KSM page,
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* no problem, it will be assigned to this vma's anon_vma; but thereafter,
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* it might be faulted into a different anon_vma (or perhaps to a different
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* offset in the same anon_vma). do_swap_page() cannot do all the locking
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* needed to reconstitute a cross-anon_vma KSM page: for now it has to make
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* a copy, and leave remerging the pages to a later pass of ksmd.
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*
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* We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
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* but what if the vma was unmerged while the page was swapped out?
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*/
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struct page *ksm_might_need_to_copy(struct page *page,
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struct vm_area_struct *vma, unsigned long address);
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int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
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void ksm_migrate_page(struct page *newpage, struct page *oldpage);
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#else /* !CONFIG_KSM */
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static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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return 0;
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}
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static inline void ksm_exit(struct mm_struct *mm)
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{
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}
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static inline int PageKsm(struct page *page)
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{
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return 0;
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}
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#ifdef CONFIG_MMU
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static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
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unsigned long end, int advice, unsigned long *vm_flags)
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{
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return 0;
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}
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static inline struct page *ksm_might_need_to_copy(struct page *page,
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struct vm_area_struct *vma, unsigned long address)
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{
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return page;
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}
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static inline int page_referenced_ksm(struct page *page,
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struct mem_cgroup *memcg, unsigned long *vm_flags)
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{
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return 0;
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}
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static inline int rmap_walk_ksm(struct page *page,
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struct rmap_walk_control *rwc)
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{
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return 0;
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}
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static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage)
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{
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}
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#endif /* CONFIG_MMU */
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#endif /* !CONFIG_KSM */
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#endif /* __LINUX_KSM_H */
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