From: Nikola Pajkovsky Subject: Re: xfstests generic/130 hang with non-4k block size ext4 on 4.7-rc1 kernel Date: Thu, 16 Jun 2016 16:42:58 +0200 Message-ID: <8737odw5xp.fsf@gooddata.com> References: <20160601165800.GI10350@eguan.usersys.redhat.com> <20160602085840.GH19636@quack2.suse.cz> <20160602121750.GC32574@quack2.suse.cz> <20160603101612.GJ10350@eguan.usersys.redhat.com> <20160603115844.GB2470@quack2.suse.cz> <20160608125631.GA19589@quack2.suse.cz> <87oa7a6d1q.fsf@gooddata.com> <20160609150405.GB19882@quack2.suse.cz> <87oa79h9on.fsf@gooddata.com> <20160616132620.GA2106@quack2.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Holger =?utf-8?Q?Hoffst=C3=A4tte?= , linux-ext4@vger.kernel.org, Jan Kara To: Jan Kara Return-path: Received: from mail-wm0-f46.google.com ([74.125.82.46]:35815 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754038AbcFPOnC convert rfc822-to-8bit (ORCPT ); Thu, 16 Jun 2016 10:43:02 -0400 Received: by mail-wm0-f46.google.com with SMTP id v199so195239302wmv.0 for ; Thu, 16 Jun 2016 07:43:01 -0700 (PDT) In-Reply-To: <20160616132620.GA2106@quack2.suse.cz> (Jan Kara's message of "Thu, 16 Jun 2016 15:26:20 +0200") Sender: linux-ext4-owner@vger.kernel.org List-ID: Jan Kara writes: > On Fri 10-06-16 07:52:56, Nikola Pajkovsky wrote: >> Jan Kara writes: >> > On Thu 09-06-16 09:23:29, Nikola Pajkovsky wrote: >> >> Holger Hoffst=C3=A4tte writes: >> >>=20 >> >> > On Wed, 08 Jun 2016 14:56:31 +0200, Jan Kara wrote: >> >> > (snip) >> >> >> Attached patch fixes the issue for me. I'll submit it once a f= ull xfstests >> >> >> run finishes for it (which may take a while as our server room= is currently >> >> >> moving to a different place). >> >> >>=20 >> >> >> Honza >> >> >> --=20 >> >> >> Jan Kara >> >> >> SUSE Labs, CR >> >> >> From 3a120841a5d9a6c42bf196389467e9e663cf1cf8 Mon Sep 17 00:00= :00 2001 >> >> >> From: Jan Kara >> >> >> Date: Wed, 8 Jun 2016 10:01:45 +0200 >> >> >> Subject: [PATCH] ext4: Fix deadlock during page writeback >> >> >>=20 >> >> >> Commit 06bd3c36a733 (ext4: fix data exposure after a crash) un= covered a >> >> >> deadlock in ext4_writepages() which was previously much harder= to hit. >> >> >> After this commit xfstest generic/130 reproduces the deadlock = on small >> >> >> filesystems. >> >> > >> >> > Since you marked this for -stable, just a heads-up that the pre= vious patch >> >> > for the data exposure was rejected from -stable (see [1]) becau= se it >> >> > has the mismatching "!IS_NOQUOTA(inode) &&" line, which didn't = exist >> >> > until 4.6. I removed it locally but Greg probably wants an offi= cial patch. >> >> > >> >> > So both this and the previous patch need to be submitted. >> >> > >> >> > [1] http://permalink.gmane.org/gmane.linux.kernel.stable/18074{= 4,5,6} >> >>=20 >> >> I'm just wondering if the Jan's patch is not related to blocked >> >> processes in following trace. It very hard to hit it and I don't = have >> >> any reproducer. >> > >> > This looks like a different issue. Does the machine recover itself= or is it >> > a hard hang and you have to press a reset button? >>=20 >> The machine is bit bigger than I have pretend. It's 18 vcpu with 160= GB >> ram and machine has dedicated mount point only for PostgreSQL data. >>=20 >> Nevertheless, I was able always to ssh to the machine, so machine it= self >> was not in hard hang and ext4 mostly gets recover by itself (it took >> 30min). But I have seen situation, were every process who 'touch' th= e ext4 >> goes immediately to D state and does not recover even after hour. > > If such situation happens, can you run 'echo w >/proc/sysrq-trigger' = to > dump stuck processes and also run 'iostat -x 1' for a while to see ho= w much > IO is happening in the system? That should tell us more. Link to 'echo w >/proc/sysrq-trigger' is here, because it's bit bigger to mail it. http://expirebox.com/download/68c26e396feb8c9abb0485f857ccea3a.html I was running iotop and there was traffic roughly ~20 KB/s write. What was bit more interesting, was looking at cat /proc/vmstat | egrep "nr_dirty|nr_writeback" nr_drity had around 240 and was slowly counting up, but nr_writeback ha= d ~8800 and was stuck for 120s. --=20 Nikola -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html