From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Tue, 24 Oct 2006 16:25:00 -0700 (PDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.168.29]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id k9ONOnaG032703 for ; Tue, 24 Oct 2006 16:24:50 -0700 Received: from pop5-1.us4.outblaze.com (pop5-1.us4.outblaze.com [205.158.62.125]) by cuda.sgi.com (Spam Firewall) with SMTP id 9F366D1A46EE for ; Tue, 24 Oct 2006 15:19:28 -0700 (PDT) Subject: Re: [PATCH] Freeze bdevs when freezing processes. From: Nigel Cunningham In-Reply-To: <20061024144446.GD11034@melbourne.sgi.com> References: <1161576735.3466.7.camel@nigel.suspend2.net> <200610231236.54317.rjw@sisk.pl> <20061024144446.GD11034@melbourne.sgi.com> Content-Type: text/plain Date: Wed, 25 Oct 2006 08:19:26 +1000 Message-Id: <1161728366.22729.28.camel@nigel.suspend2.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: David Chinner Cc: "Rafael J. Wysocki" , Andrew Morton , LKML , Pavel Machek , xfs@oss.sgi.com Hi David. On Wed, 2006-10-25 at 00:44 +1000, David Chinner wrote: > On Mon, Oct 23, 2006 at 12:36:53PM +0200, Rafael J. Wysocki wrote: > > On Monday, 23 October 2006 06:12, Nigel Cunningham wrote: > > > XFS can continue to submit I/O from a timer routine, even after > > > freezeable kernel and userspace threads are frozen. This doesn't seem to > > > be an issue for current swsusp code, > > > > So it doesn't look like we need the patch _now_. > > > > > but is definitely an issue for Suspend2, where the pages being written could > > > be overwritten by Suspend2's atomic copy. > > > > And IMO that's a good reason why we shouldn't use RCU pages for storing the > > image. XFS is one known example that breaks things if we do so and > > there may be more such things that we don't know of. The fact that they > > haven't appeared in testing so far doesn't mean they don't exist and > > moreover some things like that may appear in the future. > > Could you please tell us which XFS bits are broken so we can get > them fixed? The XFS daemons should all be checking if they are > supposed to freeze (i.e. they call try_to_freeze() after they wake > up due to timer expiry) so I thought they were doing the right > thing. The problem (in my experience) isn't the threads but a timer that submits I/O even when the threads are frozen. It stops when the bdev is frozen. The last report I've seen was before I added bdev freezing to suspend2, which was 2.6.14, so you guys may have fixed it since then. I can seek to get a trace if you like. Regards, Nigel