From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755983Ab2ARBaT (ORCPT ); Tue, 17 Jan 2012 20:30:19 -0500 Received: from mga14.intel.com ([143.182.124.37]:33141 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754260Ab2ARBaS (ORCPT ); Tue, 17 Jan 2012 20:30:18 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="57470373" Subject: Re: Kernel crash in icq_free_icq_rcu From: Shaohua Li To: Tejun Heo Cc: Vivek Goyal , linux kernel mailing list , Jens Axboe In-Reply-To: <20120118011112.GB32160@htj.dyndns.org> References: <20120117201823.GD19223@redhat.com> <20120117214834.GD26207@google.com> <20120117220715.GB23527@redhat.com> <20120118010323.GA32160@htj.dyndns.org> <20120118011112.GB32160@htj.dyndns.org> Content-Type: text/plain; charset="UTF-8" Date: Wed, 18 Jan 2012 09:30:53 +0800 Message-ID: <1326850253.22361.619.camel@sli10-conroe> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-01-17 at 17:11 -0800, Tejun Heo wrote: > On Wed, Jan 18, 2012 at 09:05:26AM +0800, Shaohua Li wrote: > > > Vivek is seeing the problem while switching elevators. Are you too? > > > Or is it during normal operation? > > same here. I had some problems when I debug my ioscheduler, but > > eventually found even switching cfq and noop can trigger oops. > > Hmmm... maybe quiescing isn't working as expected and kmem cache is > being destroyed with live icq's. I'll try to reproduce it. this debug patch seems to fix for me. diff --git a/block/blk-core.c b/block/blk-core.c index e6c05a9..c6a8ef5 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -872,11 +872,11 @@ retry: spin_unlock_irq(q->queue_lock); /* create icq if missing */ - if (unlikely(et->icq_cache && !icq)) + if (unlikely(et->icq_cache && !icq && (rw_flags & REQ_ELVPRIV))) icq = ioc_create_icq(q, gfp_mask); /* rqs are guaranteed to have icq on elv_set_request() if requested */ - if (likely(!et->icq_cache || icq)) + if (likely(!et->icq_cache || icq || !(rw_flags & REQ_ELVPRIV))) rq = blk_alloc_request(q, icq, rw_flags, gfp_mask); if (unlikely(!rq)) {