From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755329Ab0JGUN6 (ORCPT ); Thu, 7 Oct 2010 16:13:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21517 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755286Ab0JGUN4 (ORCPT ); Thu, 7 Oct 2010 16:13:56 -0400 Message-ID: <4CAE29CC.8030702@redhat.com> Date: Thu, 07 Oct 2010 22:13:00 +0200 From: Milan Broz User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100914 Thunderbird/3.1.3 MIME-Version: 1.0 To: device-mapper development CC: Tejun Heo , Linus Torvalds , Linux Kernel Mailing List , just.for.lkml@googlemail.com, hch@infradead.org, herbert@gondor.hengli.com.au Subject: Re: [dm-devel] Linux 2.6.36-rc7 References: <4CAE1F47.3050105@kernel.org> In-Reply-To: <4CAE1F47.3050105@kernel.org> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/2010 09:28 PM, Tejun Heo wrote: > I'm afraid there is a possibly workqueue related deadlock under high > memory pressure. It happens on dm-crypt + md raid1 configuration. > I'm not yet sure whether this is caused by workqueue failing to kick > rescuers under memory pressure or the shared workqueue is making an > already existing problem more visible and in the process of setting up > an environment to reproduce the problem. > > http://thread.gmane.org/gmane.comp.file-systems.xfs.general/34922/focus=1044784 Yes, XFS is very good to show up problems in dm-crypt:) But there was no change in dm-crypt which can itself cause such problem, planned workqueue changes are not in 2.6.36 yet. Code is basically the same for the last few releases. So it seems that workqueue processing really changed here under memory pressure. Milan p.s. Anyway, if you are able to reproduce it and you think that there is problem in per-device dm-crypt workqueue, there are patches from Andi for shared per-cpu workqueue, maybe it can help here. (But this is really not RC material.) Unfortunately not yet in dm-devel tree, but I have them here ready for review: http://mbroz.fedorapeople.org/dm-crypt/2.6.36-devel/ (all 4 patches must be applied, I hope Alasdair will put them in dm quilt soon.)