From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759245Ab1LPM4m (ORCPT ); Fri, 16 Dec 2011 07:56:42 -0500 Received: from merlin.infradead.org ([205.233.59.134]:44480 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756300Ab1LPM4h (ORCPT ); Fri, 16 Dec 2011 07:56:37 -0500 Message-ID: <4EEB4001.8010205@kernel.dk> Date: Fri, 16 Dec 2011 13:56:33 +0100 From: Jens Axboe MIME-Version: 1.0 To: Shaohua Li CC: lkml Subject: Re: [patch 1/2]block, cfq: fix empty queue crash caused by request merge References: <1324000362.22361.452.camel@sli10-conroe> In-Reply-To: <1324000362.22361.452.camel@sli10-conroe> X-Enigmail-Version: 1.3.4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2011-12-16 02:52, Shaohua Li wrote: > All requests of a queue could be merged to other requests of other queue. > Such queue will not have request in it, but it's in service tree. This > will cause kernel oops. > I encounter a BUG_ON() in cfq_dispatch_request() with next patch, but the > issue should exist without the patch. Good catch, yes I think this could happen if you just happen to have a very deliberate/unlucky set of processes and timings. Applied. -- Jens Axboe