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 *)stable_node +
  47                                (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
  48}
  49
  50/*
  51 * When do_swap_page() first faults in from swap what used to be a KSM page,
  52 * no problem, it will be assigned to this vma's anon_vma; but thereafter,
  53 * it might be faulted into a different anon_vma (or perhaps to a different
  54 * offset in the same anon_vma).  do_swap_page() cannot do all the locking
  55 * needed to reconstitute a cross-anon_vma KSM page: for now it has to make
  56 * a copy, and leave remerging the pages to a later pass of ksmd.
  57 *
  58 * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
  59 * but what if the vma was unmerged while the page was swapped out?
  60 */
  61struct page *ksm_might_need_to_copy(struct page *page,
  62                        struct vm_area_struct *vma, unsigned long address);
  63
  64int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
  65void ksm_migrate_page(struct page *newpage, struct page *oldpage);
  66
  67#else  /* !CONFIG_KSM */
  68
  69static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
  70{
  71        return 0;
  72}
  73
  74static inline void ksm_exit(struct mm_struct *mm)
  75{
  76}
  77
  78#ifdef CONFIG_MMU
  79static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
  80                unsigned long end, int advice, unsigned long *vm_flags)
  81{
  82        return 0;
  83}
  84
  85static inline struct page *ksm_might_need_to_copy(struct page *page,
  86                        struct vm_area_struct *vma, unsigned long address)
  87{
  88        return page;
  89}
  90
  91static inline int page_referenced_ksm(struct page *page,
  92                        struct mem_cgroup *memcg, unsigned long *vm_flags)
  93{
  94        return 0;
  95}
  96
  97static inline int rmap_walk_ksm(struct page *page,
  98                        struct rmap_walk_control *rwc)
  99{
 100        return 0;
 101}
 102
 103static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage)
 104{
 105}
 106#endif /* CONFIG_MMU */
 107#endif /* !CONFIG_KSM */
 108
 109#endif /* __LINUX_KSM_H */
 110