From 50de1dd967d4ba3b8a90ebe7a4f5feca24191317 Mon Sep 17 00:00:00 2001 From: Daisuke Nishimura Date: Thu, 13 Jan 2011 15:47:43 -0800 Subject: [PATCH] memcg: fix memory migration of shmem swapcache In the current implementation mem_cgroup_end_migration() decides whether the page migration has succeeded or not by checking "oldpage->mapping". But if we are tring to migrate a shmem swapcache, the page->mapping of it is NULL from the begining, so the check would be invalid. As a result, mem_cgroup_end_migration() assumes the migration has succeeded even if it's not, so "newpage" would be freed while it's not uncharged. This patch fixes it by passing mem_cgroup_end_migration() the result of the page migration. Signed-off-by: Daisuke Nishimura Reviewed-by: Minchan Kim Acked-by: KAMEZAWA Hiroyuki Acked-by: Balbir Singh Cc: Minchan Kim Reviewed-by: Johannes Weiner Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memcontrol.h | 5 ++--- mm/memcontrol.c | 5 ++--- mm/migrate.c | 2 +- 3 files changed, 5 insertions(+), 7 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 067115c..6a576f9 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -98,7 +98,7 @@ extern int mem_cgroup_prepare_migration(struct page *page, struct page *newpage, struct mem_cgroup **ptr); extern void mem_cgroup_end_migration(struct mem_cgroup *mem, - struct page *oldpage, struct page *newpage); + struct page *oldpage, struct page *newpage, bool migration_ok); /* * For memory reclaim. @@ -251,8 +251,7 @@ mem_cgroup_prepare_migration(struct page *page, struct page *newpage, } static inline void mem_cgroup_end_migration(struct mem_cgroup *mem, - struct page *oldpage, - struct page *newpage) + struct page *oldpage, struct page *newpage, bool migration_ok) { } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6424ba0..8ab8410 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2896,7 +2896,7 @@ int mem_cgroup_prepare_migration(struct page *page, /* remove redundant charge if migration failed*/ void mem_cgroup_end_migration(struct mem_cgroup *mem, - struct page *oldpage, struct page *newpage) + struct page *oldpage, struct page *newpage, bool migration_ok) { struct page *used, *unused; struct page_cgroup *pc; @@ -2905,8 +2905,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *mem, return; /* blocks rmdir() */ cgroup_exclude_rmdir(&mem->css); - /* at migration success, oldpage->mapping is NULL. */ - if (oldpage->mapping) { + if (!migration_ok) { used = oldpage; unused = newpage; } else { diff --git a/mm/migrate.c b/mm/migrate.c index 5b7d1fd..46fe8cc 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -768,7 +768,7 @@ skip_unmap: uncharge: if (!charge) - mem_cgroup_end_migration(mem, page, newpage); + mem_cgroup_end_migration(mem, page, newpage, rc == 0); unlock: unlock_page(page); -- 2.7.4