aboutsummaryrefslogtreecommitdiff
path: root/mm
diff options
context:
space:
mode:
authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2009-01-15 13:51:12 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-15 16:39:39 -0800
commit40d58138f832a48208cdce57d6572a033b1f7a23 (patch)
tree740c3ccefa96965cb5e27f4b13dc1e03e6f688a3 /mm
parentbd112db872c2f69993c86f458467acb4a14da010 (diff)
downloadlinux-40d58138f832a48208cdce57d6572a033b1f7a23.tar.gz
memcg: fix error path of mem_cgroup_move_parent
There is a bug in error path of mem_cgroup_move_parent. Extra refcnt got from try_charge should be dropped, and usages incremented by try_charge should be decremented in both error paths: A: failure at get_page_unless_zero B: failure at isolate_lru_page This bug makes this parent directory unremovable. In case of A, rmdir doesn't return, because res.usage doesn't go down to 0 at mem_cgroup_force_empty even after all the pc in lru are removed. In case of B, rmdir fails and returns -EBUSY, because it has extra ref counts even after res.usage goes down to 0. Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c23
1 files changed, 15 insertions, 8 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b6651277116..7be9b35d7ff 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -994,14 +994,15 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
if (pc->mem_cgroup != from)
goto out;
- css_put(&from->css);
res_counter_uncharge(&from->res, PAGE_SIZE);
mem_cgroup_charge_statistics(from, pc, false);
if (do_swap_account)
res_counter_uncharge(&from->memsw, PAGE_SIZE);
+ css_put(&from->css);
+
+ css_get(&to->css);
pc->mem_cgroup = to;
mem_cgroup_charge_statistics(to, pc, true);
- css_get(&to->css);
ret = 0;
out:
unlock_page_cgroup(pc);
@@ -1034,8 +1035,10 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
if (ret || !parent)
return ret;
- if (!get_page_unless_zero(page))
- return -EBUSY;
+ if (!get_page_unless_zero(page)) {
+ ret = -EBUSY;
+ goto uncharge;
+ }
ret = isolate_lru_page(page);
@@ -1044,19 +1047,23 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
ret = mem_cgroup_move_account(pc, child, parent);
- /* drop extra refcnt by try_charge() (move_account increment one) */
- css_put(&parent->css);
putback_lru_page(page);
if (!ret) {
put_page(page);
+ /* drop extra refcnt by try_charge() */
+ css_put(&parent->css);
return 0;
}
- /* uncharge if move fails */
+
cancel:
+ put_page(page);
+uncharge:
+ /* drop extra refcnt by try_charge() */
+ css_put(&parent->css);
+ /* uncharge if move fails */
res_counter_uncharge(&parent->res, PAGE_SIZE);
if (do_swap_account)
res_counter_uncharge(&parent->memsw, PAGE_SIZE);
- put_page(page);
return ret;
}