From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 1BF857F6B for ; Tue, 17 Feb 2015 18:48:47 -0600 (CST) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay2.corp.sgi.com (Postfix) with ESMTP id 0A9E9304032 for ; Tue, 17 Feb 2015 16:48:43 -0800 (PST) Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by cuda.sgi.com with ESMTP id VJ7h5ok0M8pqz3I1 for ; Tue, 17 Feb 2015 16:48:41 -0800 (PST) Date: Wed, 18 Feb 2015 11:48:38 +1100 From: Dave Chinner Subject: Re: [PATCH] xfs: xfs_alloc_fix_minleft can underflow near ENOSPC Message-ID: <20150218004838.GM4251@dastard> References: <1423782857-11800-1-git-send-email-david@fromorbit.com> <54DE8B6D.8010401@sgi.com> <20150214232951.GW4251@dastard> <54E16667.1050200@gmail.com> <54E22A76.40106@sgi.com> <20150216231716.GB4251@dastard> <54E36016.20908@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <54E36016.20908@gmail.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: "Michael L. Semon" Cc: Mark Tinguely , xfs@oss.sgi.com On Tue, Feb 17, 2015 at 10:36:54AM -0500, Michael L. Semon wrote: > On 02/16/15 18:17, Dave Chinner wrote: > > On Mon, Feb 16, 2015 at 11:35:50AM -0600, Mark Tinguely wrote: > >> Thanks Michael, you don't need to hold your test box for me. I do > >> have a way to recreate these ABBA AGF buffer allocation deadlocks > >> and understand the whys and hows very well. I don't have a community > >> way to make a xfstest for it but I think your test is getting close. > > > > If you know what is causing them, then please explain how it occurs > > and how you think it needs to be fixed. Just telling us that you know > > something that we don't doesn't help us solve the problem. :( > > > > In general, the use of the args->firstblock is supposed to avoid the > > ABBA locking order issues with multiple allocations in the one > > transaction by preventing AG selection loops from looping back into > > AGs with a lower index than the first allocation that was made. > > > > So if you are seeing deadlocks, then it may be that we aren't > > following this constraint correctly in all locations.... > > Will this be a classic deadlock that will cause problems when trying to > kill processes and unmount filesystems? If so, then I was unable to use > generic/224 to trigger a deadlock. If not, then I'll need a better way > of looking at the problem. Yes, it will hang the filesystem. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs