Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef __LINUX_KSM_H
       3             : #define __LINUX_KSM_H
       4             : /*
       5             :  * Memory merging support.
       6             :  *
       7             :  * This code enables dynamic sharing of identical pages found in different
       8             :  * memory areas, even if they are not shared by fork().
       9             :  */
      10             : 
      11             : #include <linux/bitops.h>
      12             : #include <linux/mm.h>
      13             : #include <linux/pagemap.h>
      14             : #include <linux/rmap.h>
      15             : #include <linux/sched.h>
      16             : #include <linux/sched/coredump.h>
      17             : 
      18             : struct stable_node;
      19             : struct mem_cgroup;
      20             : 
      21             : #ifdef CONFIG_KSM
      22             : int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
      23             :                 unsigned long end, int advice, unsigned long *vm_flags);
      24             : int __ksm_enter(struct mm_struct *mm);
      25             : void __ksm_exit(struct mm_struct *mm);
      26             : 
      27         858 : static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
      28             : {
      29         858 :         if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
      30           0 :                 return __ksm_enter(mm);
      31             :         return 0;
      32             : }
      33             : 
      34        1994 : static inline void ksm_exit(struct mm_struct *mm)
      35             : {
      36        1994 :         if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
      37           0 :                 __ksm_exit(mm);
      38        1994 : }
      39             : 
      40             : /*
      41             :  * When do_swap_page() first faults in from swap what used to be a KSM page,
      42             :  * no problem, it will be assigned to this vma's anon_vma; but thereafter,
      43             :  * it might be faulted into a different anon_vma (or perhaps to a different
      44             :  * offset in the same anon_vma).  do_swap_page() cannot do all the locking
      45             :  * needed to reconstitute a cross-anon_vma KSM page: for now it has to make
      46             :  * a copy, and leave remerging the pages to a later pass of ksmd.
      47             :  *
      48             :  * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
      49             :  * but what if the vma was unmerged while the page was swapped out?
      50             :  */
      51             : struct page *ksm_might_need_to_copy(struct page *page,
      52             :                         struct vm_area_struct *vma, unsigned long address);
      53             : 
      54             : void rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
      55             : void ksm_migrate_page(struct page *newpage, struct page *oldpage);
      56             : 
      57             : #else  /* !CONFIG_KSM */
      58             : 
      59             : static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
      60             : {
      61             :         return 0;
      62             : }
      63             : 
      64             : static inline void ksm_exit(struct mm_struct *mm)
      65             : {
      66             : }
      67             : 
      68             : #ifdef CONFIG_MMU
      69             : static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
      70             :                 unsigned long end, int advice, unsigned long *vm_flags)
      71             : {
      72             :         return 0;
      73             : }
      74             : 
      75             : static inline struct page *ksm_might_need_to_copy(struct page *page,
      76             :                         struct vm_area_struct *vma, unsigned long address)
      77             : {
      78             :         return page;
      79             : }
      80             : 
      81             : static inline void rmap_walk_ksm(struct page *page,
      82             :                         struct rmap_walk_control *rwc)
      83             : {
      84             : }
      85             : 
      86             : static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage)
      87             : {
      88             : }
      89             : #endif /* CONFIG_MMU */
      90             : #endif /* !CONFIG_KSM */
      91             : 
      92             : #endif /* __LINUX_KSM_H */