From: Tejun Heo <tj@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Akinobu Mita <akinobu.mita@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Ming Lei <tom.leiming@gmail.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v4 6/7] blk-mq: fix freeze queue race
Date: Tue, 29 Sep 2015 17:50:08 -0400 [thread overview]
Message-ID: <20150929215008.GD3578@mtj.duckdns.org> (raw)
In-Reply-To: <20150929150346.GB23411@mtj.duckdns.org>
Hello,
On Tue, Sep 29, 2015 at 11:03:46AM -0400, Tejun Heo wrote:
> On Tue, Sep 29, 2015 at 09:01:31AM -0600, Jens Axboe wrote:
> > I think that would be very useful, it seems sort of half-assed if the caller
> > side has to provide serialization for that.
>
> Yeah, the thing is init/exit are usually caller synchronized but
> percpu_rwsem's kill/reinit are more of mode-switching operations which
> can be performed concurrently during operation so I think the right
> thing to do here is making it synchronize itself. Will spin a patch.
Patchset posted
http://lkml.kernel.org/g/1443563240-29306-1-git-send-email-tj@kernel.org
Unfortunately, the required changes on percpu_ref side ended up
somewhat invasive and don't seem fit for -stable backport. I think
it'd be a good idea to apply Akinobu's patch for now and then revert
it later when the percpu_ref changes hit mainline.
Thanks.
--
tejun
next prev parent reply other threads:[~2015-09-29 21:50 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-26 17:09 [PATCH v4 0/7] blk-mq: fix race conditions on cpu hotplug handling Akinobu Mita
2015-09-26 17:09 ` [PATCH v4 1/7] blk-mq: avoid setting hctx->tags->cpumask before allocation Akinobu Mita
2015-09-26 18:12 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 2/7] blk-mq: fix sysfs registration/unregistration race Akinobu Mita
2015-09-29 6:51 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map Akinobu Mita
2015-09-29 6:52 ` Christoph Hellwig
2015-10-05 23:50 ` Akinobu Mita
2015-10-06 9:43 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 4/7] blk-mq: fix q->mq_usage_counter access race Akinobu Mita
2015-09-29 6:53 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 5/7] blk-mq: avoid inserting requests before establishing new mapping Akinobu Mita
2015-09-29 6:54 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 6/7] blk-mq: fix freeze queue race Akinobu Mita
2015-09-26 17:32 ` Tejun Heo
2015-09-27 13:06 ` Akinobu Mita
2015-09-28 14:48 ` Tejun Heo
2015-09-29 6:55 ` Christoph Hellwig
2015-09-29 15:01 ` Jens Axboe
2015-09-29 15:03 ` Tejun Heo
2015-09-29 21:50 ` Tejun Heo [this message]
2015-09-30 10:32 ` Akinobu Mita
2015-09-26 17:09 ` [PATCH v4 7/7] blk-mq: fix deadlock when reading cpu_list Akinobu Mita
2015-09-29 6:58 ` Christoph Hellwig
2015-09-29 17:31 ` [PATCH v4 0/7] blk-mq: fix race conditions on cpu hotplug handling Jens Axboe
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