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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97D12C43387 for ; Thu, 17 Jan 2019 15:24:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64C09205C9 for ; Thu, 17 Jan 2019 15:24:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727686AbfAQPYL (ORCPT ); Thu, 17 Jan 2019 10:24:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:38888 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726913AbfAQPYL (ORCPT ); Thu, 17 Jan 2019 10:24:11 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1C4B3AC97; Thu, 17 Jan 2019 15:24:10 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id B6309DA83D; Thu, 17 Jan 2019 16:23:40 +0100 (CET) Date: Thu, 17 Jan 2019 16:23:40 +0100 From: David Sterba To: Qu Wenruo Cc: dsterba@suse.cz, Josef Bacik , linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] btrfs: honor path->skip_locking in backref code Message-ID: <20190117152340.GT2900@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , Josef Bacik , linux-btrfs@vger.kernel.org, kernel-team@fb.com References: <20190116160057.22040-1-josef@toxicpanda.com> <20190117143021.GR2900@twin.jikos.cz> <3ce5bb05-5005-62f7-5174-4c7f3ebd7f8c@gmx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3ce5bb05-5005-62f7-5174-4c7f3ebd7f8c@gmx.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Jan 17, 2019 at 10:38:26PM +0800, Qu Wenruo wrote: > > > On 2019/1/17 下午10:30, David Sterba wrote: > > On Thu, Jan 17, 2019 at 09:04:13AM +0800, Qu Wenruo wrote: > >> > >> > >> On 2019/1/17 上午12:00, Josef Bacik wrote: > >>> qgroups will do the old roots lookup at delayed ref time, which could be > >>> while walking down the extent root while running a delayed ref. This > >>> should be fine, except we specifically lock eb's in the backref walking > >>> code irrespective of path->skip_locking, which deadlocks the system. > >>> Fix up the backref code to honor path->skip_locking, nobody will be > >>> modifying the commit_root when we're searching so it's completely safe > >>> to do. Thanks, > >>> > >>> Signed-off-by: Josef Bacik > >> > >> Reviewed-by: Qu Wenruo > > > > What can we use from https://patchwork.kernel.org/patch/10725371/ to > > add to the changelog? Is the deadlock caused by fb235dc06fac? > > The error and cause part should be the same. Ok, thanks I've copied the stacktrace and deadlock analysis and tags.