From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933686AbbBIRXA (ORCPT ); Mon, 9 Feb 2015 12:23:00 -0500 Received: from mail-pd0-f174.google.com ([209.85.192.174]:35503 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933306AbbBIRW7 (ORCPT ); Mon, 9 Feb 2015 12:22:59 -0500 Message-ID: <54D8ECEF.5040609@kernel.dk> Date: Mon, 09 Feb 2015 10:22:55 -0700 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Konstantin Khlebnikov , linux-kernel@vger.kernel.org CC: Tejun Heo , Vivek Goyal , stable@vger.kernel.org Subject: Re: [PATCH] cfq-iosched: handle failure of cfq group allocation References: <20150209134249.12420.97482.stgit@buzz> In-Reply-To: <20150209134249.12420.97482.stgit@buzz> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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