| #ifndef __LINUX_KSM_H |
| #define __LINUX_KSM_H |
| /* |
| * Memory merging support. |
| * |
| * This code enables dynamic sharing of identical pages found in different |
| * memory areas, even if they are not shared by fork(). |
| */ |
| |
| #include <linux/bitops.h> |
| #include <linux/mm.h> |
| #include <linux/sched.h> |
| #include <linux/vmstat.h> |
| |
| struct mmu_gather; |
| |
| #ifdef CONFIG_KSM |
| int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, int advice, unsigned long *vm_flags); |
| int __ksm_enter(struct mm_struct *mm); |
| void __ksm_exit(struct mm_struct *mm, |
| struct mmu_gather **tlbp, unsigned long end); |
| |
| static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| { |
| if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags)) |
| return __ksm_enter(mm); |
| return 0; |
| } |
| |
| /* |
| * For KSM to handle OOM without deadlock when it's breaking COW in a |
| * likely victim of the OOM killer, exit_mmap() has to serialize with |
| * ksm_exit() after freeing mm's pages but before freeing its page tables. |
| * That leaves a window in which KSM might refault pages which have just |
| * been finally unmapped: guard against that with ksm_test_exit(), and |
| * use it after getting mmap_sem in ksm.c, to check if mm is exiting. |
| */ |
| static inline bool ksm_test_exit(struct mm_struct *mm) |
| { |
| return atomic_read(&mm->mm_users) == 0; |
| } |
| |
| static inline void ksm_exit(struct mm_struct *mm, |
| struct mmu_gather **tlbp, unsigned long end) |
| { |
| if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) |
| __ksm_exit(mm, tlbp, end); |
| } |
| |
| /* |
| * A KSM page is one of those write-protected "shared pages" or "merged pages" |
| * which KSM maps into multiple mms, wherever identical anonymous page content |
| * is found in VM_MERGEABLE vmas. It's a PageAnon page, with NULL anon_vma. |
| */ |
| static inline int PageKsm(struct page *page) |
| { |
| return ((unsigned long)page->mapping == PAGE_MAPPING_ANON); |
| } |
| |
| /* |
| * But we have to avoid the checking which page_add_anon_rmap() performs. |
| */ |
| static inline void page_add_ksm_rmap(struct page *page) |
| { |
| if (atomic_inc_and_test(&page->_mapcount)) { |
| page->mapping = (void *) PAGE_MAPPING_ANON; |
| __inc_zone_page_state(page, NR_ANON_PAGES); |
| } |
| } |
| #else /* !CONFIG_KSM */ |
| |
| static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, int advice, unsigned long *vm_flags) |
| { |
| return 0; |
| } |
| |
| static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) |
| { |
| return 0; |
| } |
| |
| static inline bool ksm_test_exit(struct mm_struct *mm) |
| { |
| return 0; |
| } |
| |
| static inline void ksm_exit(struct mm_struct *mm, |
| struct mmu_gather **tlbp, unsigned long end) |
| { |
| } |
| |
| static inline int PageKsm(struct page *page) |
| { |
| return 0; |
| } |
| |
| /* No stub required for page_add_ksm_rmap(page) */ |
| #endif /* !CONFIG_KSM */ |
| |
| #endif |