From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:34192 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755316AbaDGTcX (ORCPT ); Mon, 7 Apr 2014 15:32:23 -0400 Message-ID: <5342FD3D.3090905@fb.com> Date: Mon, 7 Apr 2014 15:32:13 -0400 From: Chris Mason MIME-Version: 1.0 To: Marc MERLIN , Josef Bacik CC: Subject: Re: btrfs on 3.14rc5 stuck on "btrfs_tree_read_lock sync" References: <20140407160506.GG10789@merlins.org> <5342CE0C.3070707@fb.com> <20140407185121.GI10222@merlins.org> In-Reply-To: <20140407185121.GI10222@merlins.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 04/07/2014 02:51 PM, Marc MERLIN wrote: > On Mon, Apr 07, 2014 at 12:10:52PM -0400, Josef Bacik wrote: >> On 04/07/2014 12:05 PM, Marc MERLIN wrote: >>> I was debugging my why backup failed to run, and eventually found it was >>> stuck on sync: >>> 14080 18:18 btrfs_tree_read_lock sync >>> >>> This was hung for hours on this lock. >>> >>> Strangely, it looks like taking my sysrq-w hung the machine pretty hard for >>> close to 30sec, but this seems to have unhung sync and in the end btrfs send >>> completed after that. >>> >>> Sysqrq-w is here: >>> https://urldefense.proofpoint.com/v1/url?u=http://marc.merlins.org/tmp/sysrq-btrfs-sync-hang.txt&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=cKCbChRKsMpTX8ybrSkonQ%3D%3D%0A&m=IHXWC1Chbc0jEiUWu1v4Va9NOphtjPbjYp6yVMdUmXM%3D%0A&s=bd787a3422e9ff0972d2d09de7d424f56589aadc9d6db33e19fc44886dce604f >> >> Try Chris's integration branch in a few hours and see if that fixes >> it. Thanks, > > Mmmh, so I rebooted that server with 3.14.0 (no rc), and it was > deadlocked a long time during boot (about 10mn) before it unlocked > itself and finished booting. > > This is a bit vexing, I don't yet know which of my 3 btrfs filesystems > is causing this, and how to fix it. > After boot, it seems ok enough. > > You're recommending that I try btrfs-next on a 3.15 pre kernel, correct? > If so would it be likely to fix my filesystem and let me go back to a > stable 3.14? (I'm a bit warry about running some unstable 3.15 on it :). > Right now the fixes for this are in the integration branch on my git tree. I think we've shaken out all the problems, but if you want to wait until tomorrow I'll have it in my next branch (for linux-next). -chris