156 lines
4.0 KiB
C
156 lines
4.0 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 atomic_long_t ksm_zero_pages;
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static inline void ksm_map_zero_page(struct mm_struct *mm)
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{
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atomic_long_inc(&ksm_zero_pages);
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atomic_long_inc(&mm->ksm_zero_pages);
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}
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static inline void ksm_might_unmap_zero_page(struct mm_struct *mm, pte_t pte)
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{
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if (is_ksm_zero_pte(pte)) {
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atomic_long_dec(&ksm_zero_pages);
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atomic_long_dec(&mm->ksm_zero_pages);
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}
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}
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static inline long mm_ksm_zero_pages(struct mm_struct *mm)
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{
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return atomic_long_read(&mm->ksm_zero_pages);
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}
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static inline void ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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/* Adding mm to ksm is best effort on fork. */
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if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
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__ksm_enter(mm);
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}
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static inline int ksm_execve(struct mm_struct *mm)
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{
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if (test_bit(MMF_VM_MERGE_ANY, &mm->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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* 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 folio *ksm_might_need_to_copy(struct folio *folio,
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struct vm_area_struct *vma, unsigned long addr);
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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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void collect_procs_ksm(struct folio *folio, struct page *page,
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struct list_head *to_kill, int force_early);
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long ksm_process_profit(struct mm_struct *);
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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 void ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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}
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static inline int ksm_execve(struct mm_struct *mm)
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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(struct mm_struct *mm, pte_t pte)
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{
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}
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static inline void collect_procs_ksm(struct folio *folio, 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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#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 folio *ksm_might_need_to_copy(struct folio *folio,
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struct vm_area_struct *vma, unsigned long addr)
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{
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return folio;
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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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