From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09E40C433EF for ; Mon, 13 Jun 2022 22:05:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229808AbiFMWE6 (ORCPT ); Mon, 13 Jun 2022 18:04:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229671AbiFMWE6 (ORCPT ); Mon, 13 Jun 2022 18:04:58 -0400 Received: from mail104.syd.optusnet.com.au (mail104.syd.optusnet.com.au [211.29.132.246]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F36132B276; Mon, 13 Jun 2022 15:04:53 -0700 (PDT) Received: from dread.disaster.area (pa49-181-2-147.pa.nsw.optusnet.com.au [49.181.2.147]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id CED685ECC56; Tue, 14 Jun 2022 08:04:50 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1o0sAy-006IFI-TQ; Tue, 14 Jun 2022 08:04:48 +1000 Date: Tue, 14 Jun 2022 08:04:48 +1000 From: Dave Chinner To: Chris Mason Cc: djwong@kernel.org, hch@infradead.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, hannes@cmpxchg.org Subject: Re: [PATCH v2] iomap: skip pages past eof in iomap_do_writepage() Message-ID: <20220613220448.GY227878@dread.disaster.area> References: <20220608004228.3658429-1-clm@fb.com> <20220609005313.GX227878@dread.disaster.area> <8f4177bd-80ad-5e22-293e-5d1e944e1921@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.4 cv=deDjYVbe c=1 sm=1 tr=0 ts=62a7b484 a=ivVLWpVy4j68lT4lJFbQgw==:117 a=ivVLWpVy4j68lT4lJFbQgw==:17 a=8nJEP1OIZ-IA:10 a=JPEYwPQDsx4A:10 a=20KFwNOVAAAA:8 a=7-415B0cAAAA:8 a=dvwgNvh2vzOY59J3_fYA:9 a=wPNLvfGTeEIA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Sat, Jun 11, 2022 at 07:34:01PM -0400, Chris Mason wrote: > On 6/9/22 5:15 PM, Chris Mason wrote: > > On 6/8/22 8:53 PM, Dave Chinner wrote: > > > > Reviewed-by: Dave Chinner > > > > Thanks!  Johannes and I are both going on vacation, but I'll get an > > experiment rolled to enough hosts to see if the long tails get shorter. > >  We're unlikely to come back with results before July. > > > > Of course, the easiest way to test my theory is live patching against v5.6, > but there's a wrinkle because v5.6 still has xfs_vm_writepage() > > Looks like the iomap conversion deleted the warning that Jan was originally > fixing, and I went through some hoops to trigger skipping the pages from > inside writepage(). As you noted in the commit to delete writepage, this is > pretty hard to trigger but it does happen once I get down to a few hundred > MB free. It doesn't seem to impact fsx runs or other load, and we > unmount/xfs_repair cleanly. > > I don't like to ask people to think about ancient kernels, but am I missing > any huge problems? I've got this patch backported on v5.6, and writepage is > still in place. Just backport the patch to remove ->writepage as well? I've run test kernels since ~2017 with the writepage delete in it and never seen any problems as a result of it. That would seem to me to be the simplest way of avoiding unexpected issues with reclaim writeback and truncate races... Cheers, Dave. -- Dave Chinner david@fromorbit.com