#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/pagemap.h> #include <linux/rmap.h> #include <linux/sched.h> struct stable_node; struct mem_cgroup; #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); 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; } static inline void ksm_exit(struct mm_struct *mm) { if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) __ksm_exit(mm); } /* * 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, pointing not to any * anon_vma, but to that page's node of the stable tree. */ static inline int PageKsm(struct page *page) { return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); } static inline struct stable_node *page_stable_node(struct page *page) { return PageKsm(page) ? page_rmapping(page) : NULL; } static inline void set_page_stable_node(struct page *page, struct stable_node *stable_node) { page->mapping = (void *)stable_node + (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); } /* * When do_swap_page() first faults in from swap what used to be a KSM page, * no problem, it will be assigned to this vma's anon_vma; but thereafter, * it might be faulted into a different anon_vma (or perhaps to a different * offset in the same anon_vma). do_swap_page() cannot do all the locking * needed to reconstitute a cross-anon_vma KSM page: for now it has to make * a copy, and leave remerging the pages to a later pass of ksmd. * * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE, * but what if the vma was unmerged while the page was swapped out? */ struct page *ksm_does_need_to_copy(struct page *page, struct vm_area_struct *vma, unsigned long address); static inline struct page *ksm_might_need_to_copy(struct page *page, struct vm_area_struct *vma, unsigned long address) { struct anon_vma *anon_vma = page_anon_vma(page); if (!anon_vma || (anon_vma == vma->anon_vma && page->index == linear_page_index(vma, address))) return page; return ksm_does_need_to_copy(page, vma, address); } int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg, unsigned long *vm_flags); int try_to_unmap_ksm(struct page *page, enum ttu_flags flags); int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *, struct vm_area_struct *, unsigned long, void *), void *arg); void ksm_migrate_page(struct page *newpage, struct page *oldpage); #else /* !CONFIG_KSM */ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) { return 0; } static inline void ksm_exit(struct mm_struct *mm) { } static inline int PageKsm(struct page *page) { return 0; } #ifdef CONFIG_MMU 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 struct page *ksm_might_need_to_copy(struct page *page, struct vm_area_struct *vma, unsigned long address) { return page; } static inline int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg, unsigned long *vm_flags) { return 0; } static inline int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) { return 0; } static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page*, struct vm_area_struct *, unsigned long, void *), void *arg) { return 0; } static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage) { } #endif /* CONFIG_MMU */ #endif /* !CONFIG_KSM */ #endif /* __LINUX_KSM_H */