path: root/mm/memory.c
diff options
authorJohannes Weiner <>2013-02-22 16:32:20 -0800
committerLinus Torvalds <>2013-02-23 17:50:09 -0800
commitaf34770e55fd899c96d8d73bdc04dbc956096650 (patch)
tree91c9bfc79d765a7919412a2ab73a164c96d05706 /mm/memory.c
parent9b4f98cdac9683ee9cdb28c582a81223f0c10a3f (diff)
mm: reduce rmap overhead for ex-KSM page copies created on swap faults
When ex-KSM pages are faulted from swap cache, the fault handler is not capable of re-establishing anon_vma-spanning KSM pages. In this case, a copy of the page is created instead, just like during a COW break. These freshly made copies are known to be exclusive to the faulting VMA and there is no reason to go look for this page in parent and sibling processes during rmap operations. Use page_add_new_anon_rmap() for these copies. This also puts them on the proper LRU lists and marks them SwapBacked, so we can get rid of doing this ad-hoc in the KSM copy code. Signed-off-by: Johannes Weiner <> Reviewed-by: Rik van Riel <> Acked-by: Hugh Dickins <> Cc: Simon Jeons <> Cc: Mel Gorman <> Cc: Michal Hocko <> Cc: Satoru Moriya <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/memory.c')
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c
index bb1369f7b9b4..0abd07097ec6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3044,7 +3044,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
flush_icache_page(vma, page);
set_pte_at(mm, address, page_table, pte);
- do_page_add_anon_rmap(page, vma, address, exclusive);
+ if (swapcache) /* ksm created a completely new copy */
+ page_add_new_anon_rmap(page, vma, address);
+ else
+ do_page_add_anon_rmap(page, vma, address, exclusive);
/* It's better to call commit-charge after rmap is established */
mem_cgroup_commit_charge_swapin(page, ptr);