From: Tejun Heo <tj@kernel.org>
To: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Gioh Kim <gi-oh.kim@profitbricks.com>,
Michael Wang <yun.wang@profitbricks.com>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH 1/1] workqueue: fix ghost PENDING flag while doing MQ IO
Date: Tue, 26 Apr 2016 11:21:56 -0400 [thread overview]
Message-ID: <20160426152156.GL7822@mtj.duckdns.org> (raw)
In-Reply-To: <1461669335-19522-1-git-send-email-roman.penyaev@profitbricks.com>
Hello,
On Tue, Apr 26, 2016 at 01:15:35PM +0200, Roman Pen wrote:
...
> This behaviour can be explained by speculative LOAD of hctx->ctx_map on
> CPU#0, which is reordered with clear of PENDING bit and executed _before_
> actual STORE of bit 1 on CPU#1.
>
> The proper fix is an explicit full barrier <mfence>, which guarantees
> that clear of PENDING bit is to be executed before all possible
> speculative LOADS or STORES inside actual work function.
Applied to workqueue/for-4.6-fixes.
Thanks.
--
tejun
next prev parent reply other threads:[~2016-04-26 15:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-26 11:15 [PATCH 1/1] workqueue: fix ghost PENDING flag while doing MQ IO Roman Pen
2016-04-26 15:21 ` Tejun Heo [this message]
2016-04-26 20:58 ` Peter Hurley
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