From: Jens Axboe <axboe@kernel.dk>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
linux-kernel@vger.kernel.org
Cc: Tejun Heo <tj@kernel.org>, Vivek Goyal <vgoyal@redhat.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] cfq-iosched: handle failure of cfq group allocation
Date: Mon, 09 Feb 2015 10:22:55 -0700 [thread overview]
Message-ID: <54D8ECEF.5040609@kernel.dk> (raw)
In-Reply-To: <20150209134249.12420.97482.stgit@buzz>
On 02/09/2015 06:42 AM, 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.
Thanks, added and marked for stable as well.
--
Jens Axboe
prev parent reply other threads:[~2015-02-09 17:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-09 13:42 [PATCH] cfq-iosched: handle failure of cfq group allocation Konstantin Khlebnikov
2015-02-09 13:45 ` Tejun Heo
2015-02-09 14:06 ` Vivek Goyal
2015-02-09 17:22 ` Jens Axboe [this message]
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