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 7CC45EB64DA for ; Wed, 19 Jul 2023 05:39:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229904AbjGSFjH (ORCPT ); Wed, 19 Jul 2023 01:39:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229530AbjGSFjG (ORCPT ); Wed, 19 Jul 2023 01:39:06 -0400 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E9B3D2; Tue, 18 Jul 2023 22:39:05 -0700 (PDT) Received: by verein.lst.de (Postfix, from userid 2407) id 81A5367373; Wed, 19 Jul 2023 07:39:01 +0200 (CEST) Date: Wed, 19 Jul 2023 07:39:01 +0200 From: Christoph Hellwig To: Josef Bacik Cc: Christoph Hellwig , Chris Mason , David Sterba , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: small writeback fixes Message-ID: <20230719053901.GA3241@lst.de> References: <20230713130431.4798-1-hch@lst.de> <20230718171744.GA843162@perftesting> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230718171744.GA843162@perftesting> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Jul 18, 2023 at 01:17:44PM -0400, Josef Bacik wrote: > Just FYI I've been using these two series to see how the github CI stuff was > working, and I keep tripping over a hang in generic/475. It appears to be in > the fixup worker, here's the sysrq w output > > We appear to be getting hung up because the ENOSPC stuff is flushing and waiting > on ordered extents, and then the fixup worker is waiting on trying to reserve > space. My hunch is the page that's in the fixup worker is attached to an > ordered extent. > > I can pretty reliably reproduce this in the CI, so if you have trouble > reproducing it let me know. I'll dig into it later today, but I may not get to > it before you do. Thanks, My day was already over by the time you sent this, but I looked into it the first thing this morning. I can't reproduce the hang, but my first thought was "why the heck do even end up in the fixup worker" given that there is no GUP-based dirtying in the thread. I can reproduce the test case hitting the fixup worker now, while I can't on misc-next. Looking into it now, but the rework of the fixup logic is a hot candidate.