diff options
| -rw-r--r-- | include/linux/ksm.h | 7 | ||||
| -rw-r--r-- | mm/ksm.c | 30 | ||||
| -rw-r--r-- | mm/memory.c | 17 |
3 files changed, 50 insertions, 4 deletions
diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 481c8c4627ca..febba394f93c 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -62,6 +62,8 @@ struct page *ksm_might_need_to_copy(struct page *page, int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc); void ksm_migrate_page(struct page *newpage, struct page *oldpage); +bool reuse_ksm_page(struct page *page, + struct vm_area_struct *vma, unsigned long address); #else /* !CONFIG_KSM */ @@ -102,6 +104,11 @@ static inline int rmap_walk_ksm(struct page *page, static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage) { } +static inline bool reuse_ksm_page(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + return false; +} #endif /* CONFIG_MMU */ #endif /* !CONFIG_KSM */ @@ -580,8 +580,9 @@ again: * case this node is no longer referenced, and should be freed; * however, it might mean that the page is under page_freeze_refs(). * The __remove_mapping() case is easy, again the node is now stale; - * but if page is swapcache in migrate_page_move_mapping(), it might - * still be our page, in which case it's essential to keep the node. + * the same is in reuse_ksm_page() case; but if page is swapcache + * in migrate_page_move_mapping(), it might still be our page, + * in which case it's essential to keep the node. */ while (!get_page_unless_zero(page)) { /* @@ -2061,6 +2062,31 @@ out: return ret; } +bool reuse_ksm_page(struct page *page, + struct vm_area_struct *vma, + unsigned long address) +{ +#ifdef CONFIG_DEBUG_VM + if (WARN_ON(is_zero_pfn(page_to_pfn(page))) || + WARN_ON(!page_mapped(page)) || + WARN_ON(!PageLocked(page))) { + dump_page(page, "reuse_ksm_page"); + return false; + } +#endif + + if (PageSwapCache(page) || !page_stable_node(page)) + return false; + /* Prohibit parallel get_ksm_page() */ + if (!page_ref_freeze(page, 1)) + return false; + + page_move_anon_rmap(page, vma); + page->index = linear_page_index(vma, address); + page_ref_unfreeze(page, 1); + + return true; +} #ifdef CONFIG_MIGRATION void ksm_migrate_page(struct page *newpage, struct page *oldpage) { diff --git a/mm/memory.c b/mm/memory.c index 09a57fe6ae01..ccb04d3f9bab 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2399,7 +2399,10 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, * Take out anonymous pages first, anonymous shared vmas are * not dirty accountable. */ - if (PageAnon(old_page) && !PageKsm(old_page)) { + if (PageAnon(old_page)) { + if (PageKsm(old_page) && (PageSwapCache(old_page) || + page_count(old_page) != 1)) + goto copy; if (!trylock_page(old_page)) { page_cache_get(old_page); pte_unmap_unlock(page_table, ptl); @@ -2414,6 +2417,16 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, } page_cache_release(old_page); } + if (PageKsm(old_page)) { + bool reused = reuse_ksm_page(old_page, vma, + address); + unlock_page(old_page); + if (!reused) + goto copy; + wp_page_reuse(mm, vma, address, page_table, ptl, + orig_pte, old_page, 0, 0); + return VM_FAULT_WRITE; + } if (reuse_swap_page(old_page)) { /* * The page is all ours. Move it to our anon_vma so @@ -2431,7 +2444,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, return wp_page_shared(mm, vma, address, page_table, pmd, ptl, orig_pte, old_page); } - +copy: /* * Ok, we need to copy. Oh, well.. */ |