Messages in this thread Patch in this message | | | Date | Sun, 06 Dec 2009 16:00:11 -0800 | From | Greg KH <> | Subject | [035/119] memcg: fix wrong pointer initialization at page migration when memcg is disabled. |
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2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
commit e00e431612c3a6e437a01f2129fd3843da0c982a upstream.
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/migrate.c +++ b/mm/migrate.c @@ -597,7 +597,7 @@ static int unmap_and_move(new_page_t get 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;
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