On Wed, 3 Mar 2010 16:23:04 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Wed, 3 Mar 2010 09:38:44 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>
> > On Wed, 3 Mar 2010 09:26:06 +0900
> > Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote:
> >
> > > > I'll test this patch all through this night, and check whether it doesn't trigger
> > > > global oom after memcg's oom.
> > > >
> > > O.K. It works well.
> > > Feel free to add my signs.
> > >
> > > Reviewed-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
> > > Tested-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
> > >
> >
> > Thank you !
> >
> > I'll apply Balbir's comment and post v3.
> >
>
> rebased onto mmotm-Mar2.
> tested on x86-64.
>
I found a small race problem. This is the fix for it.
===
From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
We must avoid making oom_lock of a newly created child be negative.
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3ce8c5b..9e25400 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1272,7 +1272,12 @@ static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data)
{
- atomic_dec(&mem->oom_lock);
+ /*
+ * There is a small race window where a new child can be created after
+ * we called mem_cgroup_oom_lock(). Use atomic_add_unless() to avoid
+ * making oom_lock of such a child be negative.
+ */
+ atomic_add_unless(&mem->oom_lock, -1, 0);
return 0;
}
--
1.6.4
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