From: Luis Henriques <henrix@camandro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Yong Zhang <yong.zhang0@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH -rt] memcg: use migrate_disable()/migrate_enable( ) in memcg_check_events()
Date: Wed, 16 Nov 2011 17:18:09 +0000 [thread overview]
Message-ID: <20111116171809.GA1999@hades> (raw)
In-Reply-To: <alpine.LFD.2.02.1111161801270.4902@ionos>
On Wed, Nov 16, 2011 at 06:02:42PM +0100, Thomas Gleixner wrote:
> On Wed, 16 Nov 2011, Steven Rostedt wrote:
> > On Wed, 2011-11-16 at 17:16 +0800, Yong Zhang wrote:
> > > Looking at commit 4799401f [memcg: Fix race condition in
> > > memcg_check_events() with this_cpu usage], we just want
> > > to disable migration. So use the right API in -rt. This
> > > will cure below warning.
> > No this won't work. Not even for -rt. If we disable migration but not
> > preemption, then two tasks can take this path. And the checks in
> > __memcg_event_check() will be corrupted because nothing is protecting
> > the updates from two tasks going into the same path.
> >
> > Perhaps a local_lock would work.
>
> Yes, that's the only sensible option for now. Untested patch below.
I run a quick test and it looks like the problem is gone.
Cheers,
--
Luis Henriques
next prev parent reply other threads:[~2011-11-16 17:18 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-15 1:15 [ANNOUNCE] 3.2-rc1-rt2 Thomas Gleixner
2011-11-15 8:40 ` Yong Zhang
2011-11-15 13:52 ` Luis Henriques
2011-11-16 9:16 ` [PATCH -rt] memcg: use migrate_disable()/migrate_enable( ) in memcg_check_events() Yong Zhang
2011-11-16 14:12 ` Steven Rostedt
2011-11-16 17:02 ` Thomas Gleixner
2011-11-16 17:18 ` Luis Henriques [this message]
2011-11-16 23:48 ` KAMEZAWA Hiroyuki
2011-11-17 0:23 ` Steven Rostedt
2011-11-17 3:03 ` Yong Zhang
2011-11-17 10:25 ` Thomas Gleixner
2011-11-17 11:44 ` Luis Henriques
2011-11-17 11:59 ` Thomas Gleixner
2011-11-18 7:08 ` Yong Zhang
2011-11-17 2:15 ` Yong Zhang
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