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 5CD977F3F for ; Mon, 16 Feb 2015 17:23:02 -0600 (CST) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 3CD91304039 for ; Mon, 16 Feb 2015 15:22:58 -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 j1PUDkTm5CoSYvCU for ; Mon, 16 Feb 2015 15:22:56 -0800 (PST) Date: Tue, 17 Feb 2015 10:17:16 +1100 From: Dave Chinner Subject: Re: [PATCH] xfs: xfs_alloc_fix_minleft can underflow near ENOSPC Message-ID: <20150216231716.GB4251@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> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <54E22A76.40106@sgi.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: Mark Tinguely Cc: "Michael L. Semon" , xfs@oss.sgi.com 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.... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs