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From: Tejun Heo <tj@kernel.org>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-kernel@vger.kernel.org, Vivek Goyal <vgoyal@redhat.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH] cfq-iosched: handle failure of cfq group allocation
Date: Mon, 9 Feb 2015 08:45:37 -0500	[thread overview]
Message-ID: <20150209134537.GG3220@htj.duckdns.org> (raw)
In-Reply-To: <20150209134249.12420.97482.stgit@buzz>

On Mon, Feb 09, 2015 at 04:42:49PM +0300, Konstantin Khlebnikov wrote:
> Cfq_lookup_create_cfqg() allocates struct blkcg_gq using GFP_ATOMIC.
> In cfq_find_alloc_queue() possible allocation failure is not handled.
> As a result kernel oopses on NULL pointer dereference when
> cfq_link_cfqq_cfqg() calls cfqg_get() for NULL pointer.
> 
> Bug was introduced in v3.5 in commit cd1604fab4f9 ("blkcg: factor
> out blkio_group creation"). Prior to that commit cfq group lookup
> had returned pointer to root group as fallback.
> 
> This patch handles this error using existing fallback oom_cfqq.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

Oops,

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

  reply	other threads:[~2015-02-09 13:45 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-09 13:42 Konstantin Khlebnikov
2015-02-09 13:45 ` Tejun Heo [this message]
2015-02-09 14:06 ` Vivek Goyal
2015-02-09 17:22 ` Jens Axboe

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