From: Tejun Heo <tj@kernel.org>
To: Olof Johansson <olof@lixom.net>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, vgoyal@redhat.com,
torvalds@linux-foundation.org
Subject: Re: [REGRESSION] [PATCH] block: uninitialized ioc->nr_tasks triggers WARN_ON
Date: Tue, 17 Jul 2012 15:24:44 -0700 [thread overview]
Message-ID: <20120717222444.GG24336@google.com> (raw)
In-Reply-To: <20120717213643.GA24726@quad.lixom.net>
Hello, Olof.
On Tue, Jul 17, 2012 at 02:36:43PM -0700, Olof Johansson wrote:
> It seems like the init of ioc->nr_tasks was removed in that patch,
> so it starts out at 0 instead of 1.
>
> Tejun, is the right thing here to add back the init, or should something else
> be done?
>
> The below patch removes the warning, but I haven't done any more extensive
> testing on it.
>
>
> Signed-off-by: Olof Johansson <olof@lixom.net>
Right, the patch shouldn't have replaced the init.
Acked-by: Tejun Heo <tj@kernel.org>
Fortunately, the effect of the bug is limited. ioc->nr_tasks only
used to veto block cgroup migration if a task has ioc which is shared
by multiple tasks. Currently, the only known program using CLONE_IO
is dump and even if somebody migrates some threads of a single dump
instance to a different block cgroup, the result won't be catastrophic
although block cgroup policies would become ambiguous. IMHO, it
should be okay to route this through -stable after 3.5. Jens?
Thanks.
--
tejun
next prev parent reply other threads:[~2012-07-17 22:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-17 21:36 [REGRESSION] [PATCH] block: uninitialized ioc->nr_tasks triggers WARN_ON Olof Johansson
2012-07-17 22:24 ` Tejun Heo [this message]
2012-07-24 13:35 ` Maxim V. Patlasov
2012-07-24 18:18 ` Tejun Heo
2012-08-01 10:16 ` Jens Axboe
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