80 lines
1.9 KiB
C
80 lines
1.9 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/sched.h>
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#include <linux/vmstat.h>
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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, with NULL anon_vma.
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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_ANON);
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}
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/*
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* But we have to avoid the checking which page_add_anon_rmap() performs.
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*/
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static inline void page_add_ksm_rmap(struct page *page)
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{
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if (atomic_inc_and_test(&page->_mapcount)) {
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page->mapping = (void *) PAGE_MAPPING_ANON;
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__inc_zone_page_state(page, NR_ANON_PAGES);
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}
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}
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#else /* !CONFIG_KSM */
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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 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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/* No stub required for page_add_ksm_rmap(page) */
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#endif /* !CONFIG_KSM */
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#endif
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