From: Tejun Heo <tj@kernel.org>
To: Roman Penyaev <roman.penyaev@profitbricks.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>,
Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/1] blk-mq: fix hang caused by freeze/unfreeze sequence
Date: Wed, 10 Aug 2016 14:54:05 -0400 [thread overview]
Message-ID: <20160810185405.GN25053@mtj.duckdns.org> (raw)
In-Reply-To: <CAJrWOzCWfMN7qKipgWn2P0dfycu4y5DQysD+7Q1UANgXBgw0+g@mail.gmail.com>
On Wed, Aug 10, 2016 at 10:42:09AM +0200, Roman Penyaev wrote:
> Hi,
>
> On Wed, Aug 10, 2016 at 5:55 AM, Tejun Heo <tj@kernel.org> wrote:
> > Hello,
> >
> > On Mon, Aug 08, 2016 at 01:39:08PM +0200, Roman Pen wrote:
> >> Long time ago there was a similar fix proposed by Akinobu Mita[1],
> >> but it seems that time everyone decided to fix this subtle race in
> >> percpu-refcount and Tejun Heo[2] did an attempt (as I can see that
> >> patchset was not applied).
> >
> > So, I probably forgot about it while waiting for confirmation of fix.
> > Can you please verify that the patchset fixes the issue? I can apply
> > the patchset right away.
>
> I have not checked your patchset but according to my understanding
> it should not fix *this* issue. What happens here is a wrong order
> of invocation of percpu_ref_reinit() and percpu_ref_kill(). So what
> was observed is the following:
Ah, understood.
Acked-by: Tejun Heo <tj@kernel.org>
I'll commit the percpu_refcnt patches too. While they don't fix the
problem on their own, the changes are generally useful for all mode
switching use cases.
Thanks.
--
tejun
prev parent reply other threads:[~2016-08-10 18:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-08 11:39 Roman Pen
2016-08-10 3:55 ` Tejun Heo
2016-08-10 8:42 ` Roman Penyaev
2016-08-10 11:36 ` Roman Penyaev
2016-08-30 9:37 ` 王金浦
2016-08-10 18:54 ` Tejun Heo [this message]
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