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e2942062e0
As pages_sharing and pages_shared don't include the number of zero pages merged by KSM, we cannot know how many pages are zero pages placed by KSM when enabling use_zero_pages, which leads to KSM not being transparent with all actual merged pages by KSM. In the early days of use_zero_pages, zero-pages was unable to get unshared by the ways like MADV_UNMERGEABLE so it's hard to count how many times one of those zeropages was then unmerged. But now, unsharing KSM-placed zero page accurately has been achieved, so we can easily count both how many times a page full of zeroes was merged with zero-page and how many times one of those pages was then unmerged. and so, it helps to estimate memory demands when each and every shared page could get unshared. So we add ksm_zero_pages under /sys/kernel/mm/ksm/ to show the number of all zero pages placed by KSM. Meanwhile, we update the Documentation. Link: https://lkml.kernel.org/r/20230613030934.185944-1-yang.yang29@zte.com.cn Signed-off-by: xu xin <xu.xin16@zte.com.cn> Acked-by: David Hildenbrand <david@redhat.com> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn> Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn> Reviewed-by: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
147 lines
3.7 KiB
C
147 lines
3.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#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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#include <linux/sched/coredump.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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void ksm_add_vma(struct vm_area_struct *vma);
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int ksm_enable_merge_any(struct mm_struct *mm);
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int ksm_disable_merge_any(struct mm_struct *mm);
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int ksm_disable(struct mm_struct *mm);
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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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/*
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* To identify zeropages that were mapped by KSM, we reuse the dirty bit
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* in the PTE. If the PTE is dirty, the zeropage was mapped by KSM when
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* deduplicating memory.
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*/
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#define is_ksm_zero_pte(pte) (is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte))
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extern unsigned long ksm_zero_pages;
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static inline void ksm_might_unmap_zero_page(pte_t pte)
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{
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if (is_ksm_zero_pte(pte))
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ksm_zero_pages--;
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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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int ret;
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if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) {
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ret = __ksm_enter(mm);
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if (ret)
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return ret;
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}
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if (test_bit(MMF_VM_MERGE_ANY, &oldmm->flags))
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set_bit(MMF_VM_MERGE_ANY, &mm->flags);
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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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* 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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void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc);
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void folio_migrate_ksm(struct folio *newfolio, struct folio *folio);
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#ifdef CONFIG_MEMORY_FAILURE
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void collect_procs_ksm(struct page *page, struct list_head *to_kill,
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int force_early);
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#endif
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#ifdef CONFIG_PROC_FS
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long ksm_process_profit(struct mm_struct *);
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#endif /* CONFIG_PROC_FS */
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#else /* !CONFIG_KSM */
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static inline void ksm_add_vma(struct vm_area_struct *vma)
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{
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}
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static inline int ksm_disable(struct mm_struct *mm)
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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 void ksm_might_unmap_zero_page(pte_t pte)
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{
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}
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#ifdef CONFIG_MEMORY_FAILURE
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static inline void collect_procs_ksm(struct page *page,
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struct list_head *to_kill, int force_early)
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{
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}
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#endif
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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 void rmap_walk_ksm(struct folio *folio,
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struct rmap_walk_control *rwc)
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{
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}
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static inline void folio_migrate_ksm(struct folio *newfolio, struct folio *old)
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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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