From e00e431612c3a6e437a01f2129fd3843da0c982a Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Date: Wed, 11 Nov 2009 14:26:26 -0800 Subject: [PATCH] memcg: fix wrong pointer initialization at page migration when memcg is disabled. Lee Schermerhorn reported that he saw bad pointer dereference in mem_cgroup_end_migration() when he disabled memcg by boot option. memcg's page migration logic works as mem_cgroup_prepare_migration(page, &ptr); do page migration mem_cgroup_end_migration(page, ptr); Now, ptr is not initialized in prepare_migration when memcg is disabled by boot option. This causes panic in end_migration. This patch fixes it. Reported-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index 1a4bf4813780e..7dbcb22316d2b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -602,7 +602,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, struct page *newpage = get_new_page(page, private, &result); int rcu_locked = 0; int charge = 0; - struct mem_cgroup *mem; + struct mem_cgroup *mem = NULL; if (!newpage) return -ENOMEM; -- GitLab