LXR linux/include/linux/ksm.h

   1#ifndef __LINUX_KSM_H
   2#define __LINUX_KSM_H
   3/*
   4 * Memory merging support.
   5 *
   6 * This code enables dynamic sharing of identical pages found in different
   7 * memory areas, even if they are not shared by fork().
   8 */
   9
  10#include <linux/bitops.h>
  11#include <linux/mm.h>
  12#include <linux/pagemap.h>
  13#include <linux/rmap.h>
  14#include <linux/sched.h>
  15
  16struct stable_node;
  17struct mem_cgroup;
  18
  19#ifdef CONFIG_KSM
  20int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
  21                unsigned long end, int advice, unsigned long *vm_flags);
  22int __ksm_enter(struct mm_struct *mm);
  23void __ksm_exit(struct mm_struct *mm);
  24
  25static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
  26{
  27        if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
  28                return __ksm_enter(mm);
  29        return 0;
  30}
  31
  32static inline void ksm_exit(struct mm_struct *mm)
  33{
  34        if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
  35                __ksm_exit(mm);
  36}
  37
  38static inline struct stable_node *page_stable_node(struct page *page)
  39{
  40        return PageKsm(page) ? page_rmapping(page) : NULL;
  41}
  42
  43static inline void set_page_stable_node(struct page *page,
  44                                        struct stable_node *stable_node)
  45{
  46        page->mapping = (void *)((unsigned long)stable_node | PAGE_MAPPING_KSM);
  47}
  48
  49/*
  50 * When do_swap_page() first faults in from swap what used to be a KSM page,
  51 * no problem, it will be assigned to this vma's anon_vma; but thereafter,
  52 * it might be faulted into a different anon_vma (or perhaps to a different
  53 * offset in the same anon_vma).  do_swap_page() cannot do all the locking
  54 * needed to reconstitute a cross-anon_vma KSM page: for now it has to make
  55 * a copy, and leave remerging the pages to a later pass of ksmd.
  56 *
  57 * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
  58 * but what if the vma was unmerged while the page was swapped out?
  59 */
  60struct page *ksm_might_need_to_copy(struct page *page,
  61                        struct vm_area_struct *vma, unsigned long address);
  62
  63int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
  64void ksm_migrate_page(struct page *newpage, struct page *oldpage);
  65
  66#else  /* !CONFIG_KSM */
  67
  68static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
  69{
  70        return 0;
  71}
  72
  73static inline void ksm_exit(struct mm_struct *mm)
  74{
  75}
  76
  77#ifdef CONFIG_MMU
  78static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
  79                unsigned long end, int advice, unsigned long *vm_flags)
  80{
  81        return 0;
  82}
  83
  84static inline struct page *ksm_might_need_to_copy(struct page *page,
  85                        struct vm_area_struct *vma, unsigned long address)
  86{
  87        return page;
  88}
  89
  90static inline int page_referenced_ksm(struct page *page,
  91                        struct mem_cgroup *memcg, unsigned long *vm_flags)
  92{
  93        return 0;
  94}
  95
  96static inline int rmap_walk_ksm(struct page *page,
  97                        struct rmap_walk_control *rwc)
  98{
  99        return 0;
 100}
 101
 102static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage)
 103{
 104}
 105#endif /* CONFIG_MMU */
 106#endif /* !CONFIG_KSM */
 107
 108#endif /* __LINUX_KSM_H */
 109