linux-ext4 - Re: ext4: journal has aborted

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAFnufp2yDsbHby6Ye-Ldjz=qGWyxOJUMv8JZJa-5+f6CUFSpYw@mail.gmail.com>
Date:	Thu, 10 Jul 2014 23:31:14 +0200
From:	Matteo Croce <technoboy85@...il.com>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
Cc:	Eric Whitney <enwlinux@...il.com>, "Theodore Ts'o" <tytso@....edu>,
	David Jander <david@...tonic.nl>,
	Dmitry Monakhov <dmonakhov@...nvz.org>,
	linux-ext4@...r.kernel.org
Subject: Re: ext4: journal has aborted

Will do, thanks!

2014-07-10 22:01 GMT+02:00 Darrick J. Wong <darrick.wong@...cle.com>:
> On Thu, Jul 10, 2014 at 02:57:48PM -0400, Eric Whitney wrote:
>> * Theodore Ts'o <tytso@....edu>:
>> > On Mon, Jul 07, 2014 at 11:53:10AM -0400, Theodore Ts'o wrote:
>> > > An update from today's ext4 concall.  Eric Whitney can fairly reliably
>> > > reproduce this on his Panda board with 3.15, and definitely not on
>> > > 3.14.  So at this point there seems to be at least some kind of 3.15
>> > > regression going on here, regardless of whether it's in the eMMC
>> > > driver or the ext4 code.  (It also means that the bug fix I found is
>> > > irrelevant for the purposes of working this issue, since that's a much
>> > > harder to hit, and that bug has been around long before 3.14.)
>> > >
>> > > The problem in terms of narrowing it down any further is that the
>> > > Pandaboard is running into RCU bugs which makes it hard to test the
>> > > early 3.15-rcX kernels.....
>> >
>> > In the hopes of making it easy to bisect, I've created a kernel branch
>> > which starts with 3.14, and then adds on all of the ext4-related
>> > commits since then.   You can find it at:
>> >
>> > git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git test-mb_generate_buddy-failure
>> >
>> > https://git.kernel.org/cgit/linux/kernel/git/tytso/ext4.git/log/?h=test-mb_generate_buddy-failure
>> >
>> > Eric, can you see if you can repro the failure on your Panda Board?
>> > If you can, try doing a bisection search on these series:
>> >
>> > git bisect start
>> > git bisect good v3.14
>> > git bisect bad test-mb_generate_buddy-failure
>> >
>> > Hopefully if it is caused by one of the commits in this series, we'll
>> > be able to pin point it this way.
>>
>> First, the good news (with luck):
>>
>> My testing currently suggests that the patch causing this regression was
>> pulled into 3.15-rc3 -
>>
>> 007649375f6af242d5b1df2c15996949714303ba
>> ext4: initialize multi-block allocator before checking block descriptors
>>
>> Bisection by selectively reverting ext4 commits in -rc3 identified this patch
>> while running on the Pandaboard.  I'm still using generic/068 as my reproducer.
>> It occasionally yields a false negative, but it has passed 10 consecutive
>> trials on my revert/bisect kernel derived from 3.15-rc3.  Given the frequency
>> of false negatives I've seen, I'm reasonably confident in that result.  I'm
>> going to run another series with just that patch reverted on 3.16-rc3.
>>
>> Looking at the patch, the call to ext4_mb_init() was hoisted above the code
>> performing journal recovery in ext4_fill_super().  The regression occurs only
>> after journal recovery on the root filesystem.
>
> Thanks for finding the culprit! :)
>
> Can you apply this patch, build with CONFIG_EXT4FS_DEBUG=y, and see if an
> FS will mount without crashing?  This was the cruddy patch I sent in (and later
> killed) that fixed the crash on mount with EXT4FS_DEBUG in a somewhat silly
> way.  Maybe it's appropriate now.
> http://www.spinics.net/lists/linux-ext4/msg43287.html
>
> --D
>
>>
>> Secondly:
>>
>> Thanks for that git tree!  However, I discovered that the same "RCU bug" I
>> thought I was seeing on the Panda was also visible on the x86_64 KVM, and
>> it was actually just RCU noticing stalls.  These also occurred when using
>> your git tree as well as on mainline 3.15-rc1 and 3.15-rc2 and during
>> bisection attempts on 3.15-rc3 within the ext4 patches, and had the effect of
>> masking the regression on the root filesystem.  The test system would lock up
>> completely - no console response - and made it impossible to force the reboot
>> which was required to set up the failure.  Hence the reversion approach, since
>> RCU does not report stalls in 3.15-rc3 (final).
>>
>> Eric
>>
>>
>>
>> >
>> > Thanks!!
>> >
>> >                                             - Ted
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>> the body of a message to majordomo@...r.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html



-- 
Matteo Croce
OpenWrt Developer
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html