From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail06.adl2.internode.on.net ([150.101.137.129]:51421 "EHLO ipmail06.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726258AbeJFGiW (ORCPT ); Sat, 6 Oct 2018 02:38:22 -0400 Date: Sat, 6 Oct 2018 09:37:21 +1000 From: Dave Chinner To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH] writeback: fix range_cyclic writeback vs writepages deadlock Message-ID: <20181005233721.GI12041@dastard> References: <20181005054526.21507-1-david@fromorbit.com> <20181005124640.3de2ba9dec8c713ee8cf286b@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181005124640.3de2ba9dec8c713ee8cf286b@linux-foundation.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, Oct 05, 2018 at 12:46:40PM -0700, Andrew Morton wrote: > On Fri, 5 Oct 2018 15:45:26 +1000 Dave Chinner wrote: > > > From: Dave Chinner > > > > We've recently seen a workload on XFS filesystems with a repeatable > > deadlock between background writeback and a multi-process > > application doing concurrent writes and fsyncs to a small range of a > > file. > > > > ... > > > > Signed-off-by: Dave Chinner > > Reviewed-by: Jan Kara > > Not a serious enough problem for a -stable backport? Don't have enough evidence to say one way or another. The reported incident was from a RHEL 7 kernel, so the bug has been there for years in one form or another, but it's only ever been triggered by this one-off custom workload. I haven't done any analysis on older kernels, nor have I looked to see if there's any gotchas that a stable backport might encounter. And I tend not to change stuff in a path that is critical to data integrity without at least doing enough due diligence to suggest a stable backport would be fine. You can mark it for stable backports if you want, but I'm not prepared to because I haven't done the work necessary to ensure it's safe to do so. Cheers, Dave. -- Dave Chinner david@fromorbit.com