Date: Tue, 29 Jul 2014 11:14:15 -0400
From: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@gentwo.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Sasha Levin <sasha.levin@oracle.com>, akpm@linux-foundation.org,
        Gilad Ben-Yossef <gilad@benyossef.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        John Stultz <johnstul@us.ibm.com>, Mike Frysinger <vapier@gentoo.org>,
        Minchan Kim <minchan.kim@gmail.com>,
        Hakan Akkan <hakanakkan@gmail.com>,
        Max Krasnyansky <maxk@qualcomm.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org, hughd@google.com,
        viresh.kumar@linaro.org, hpa@zytor.com, mingo@kernel.org,
        Lai Jiangshan <laijs@cn.fujitsu.com>
Subject: Re: vmstat: On demand vmstat workers V8
Message-ID: <20140729151415.GF4791@htj.dyndns.org>
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On Tue, Jul 29, 2014 at 10:10:11AM -0500, Christoph Lameter wrote:
> On Tue, 29 Jul 2014, Tejun Heo wrote:
> 
> > I agree this can be improved, but at least for now, please add cpu
> > down hooks.  We need them right now and they'll be helpful when later
> > separating out the correctness ones.
> 
> mm/vmstat.c already has cpu down hooks. See vmstat_cpuup_callback().

Hmmm, well, then it's something else.  Either a bug in workqueue or in
the caller.  Given the track record, the latter is more likely.
e.g. it looks kinda suspicious that the work func is cleared after
cancel_delayed_work_sync() is called.  What happens if somebody tries
to schedule it inbetween?

Thanks.

-- 
tejun
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