[BUGFIX][PATCH] memcg fix wake up in oom wait queue

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Tested on mmotm-2010-06-03 and works well.
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

OOM-waitqueue should be waken up when oom_disable is canceled.
This is a fix for
 memcg-oom-kill-disable-and-oom-status.patch

How to test:
 Create a cgroup A...
 1. set memory.limit and memory.memsw.limit to be small value
 2. echo 1 > /cgroup/A/memory.oom_control, this disables oom-kill.
 3. run a program which must cause OOM.

A program executed in 3 will sleep by oom_waiqueue in memcg.
Then, how to wake it up is problem.

 1. echo 0 > /cgroup/A/memory.oom_control (enable OOM-killer)
 2. echo big mem > /cgroup/A/memory.memsw.limit_in_bytes(allow more swap)
etc..

Without the patch, a task in slept can not be waken up.

Changelog: 2010/06/04
Rebased onto mmotm-2010-06-03-16-36

Acked-by: Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 mm/memcontrol.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: mmotm-2.6.34-Jun6/mm/memcontrol.c
===================================================================
--- mmotm-2.6.34-Jun6.orig/mm/memcontrol.c
+++ mmotm-2.6.34-Jun6/mm/memcontrol.c
@@ -1370,7 +1370,7 @@ static void memcg_wakeup_oom(struct mem_
 
 static void memcg_oom_recover(struct mem_cgroup *mem)
 {
-	if (mem->oom_kill_disable && atomic_read(&mem->oom_lock))
+	if (atomic_read(&mem->oom_lock))
 		memcg_wakeup_oom(mem);
 }
 
@@ -3781,6 +3781,8 @@ static int mem_cgroup_oom_control_write(
 		return -EINVAL;
 	}
 	mem->oom_kill_disable = val;
+	if (!val)
+		memcg_oom_recover(mem);
 	cgroup_unlock();
 	return 0;
 }

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>