Re: ext4: journal has aborted

[David Jander <david@protonic.nl>]

Hi Ted,

On Thu, 3 Jul 2014 09:43:38 -0400
"Theodore Ts'o" <tytso@mit.edu> wrote:

> On Tue, Jul 01, 2014 at 10:55:11AM +0200, Matteo Croce wrote:
> > 2014-07-01 10:42 GMT+02:00 Darrick J. Wong <darrick.wong@oracle.com>:
> > 
> > I have a Samsung SSD 840 PRO
> 
> Matteo,
> 
> For you, you said you were seeing these problems on 3.15.  Was it
> *not* happening for you when you used an older kernel?  If so, that
> would help us try to provide the basis of trying to do a bisection
> search.

I also tested with 3.15, and there too I see the same problem.

> Using the kvm-xfstests infrastructure, I've been trying to reproduce
> the problem as follows:
> 
> ./kvm-xfstests  --no-log -c 4k generic/075 ; e2fsck -p /dev/heap/test-4k ; e2fsck -f /dev/heap/test-4k 
> 
> xfstests geneeric/075 runs fsx which does a fair amount of block
> allocation deallocations, and then after the test finishes, it first
> replays the journal (e2fsck -p) and then forces a fsck run on the
> test disk that I use for the run.
> 
> After I launch this, in a separate window, I do this:
> 
> 	sleep 60  ; killall qemu-system-x86_64 
> 
> This kills the qemu process midway through the fsx test, and then I
> see if I can find a problem.  I haven't had a chance to automate this
> yet, and it is my intention to try to set this up where I can run this
> on a ramdisk or a SSD, so I can more closely approximate what people
> are reporting on flash-based media.
> 
> So far, I haven't been able to reproduce the problem.  If after doing
> a large number of times, it can't be reproduced (especially if it
> can't be reproduced on an SSD), then it would lead us to believe that
> one of two things is the cause.  (a) The CACHE FLUSH command isn't
> properly getting sent to the device in some cases, or (b) there really
> is a hardware problem with the flash device in question.

Could (a) be caused by a bug in the mmc subsystem or in the MMC peripheral
driver? Can you explain why I don't see any problems with EXT3?

I can't discard the possibility of (b) because I cannot prove it, but I will
try to see if I can do the same test on a SSD which I happen to have on that
platform. That should be able to rule out problems with the eMMC chip and
-driver, right?

Do you know a way to investigate (a) (CACHE FLUSH not being sent correctly)?

I left the system running (it started from a dirty EXT4 partition), and I am
seen the following error pop up after a few minutes. The system is not doing
much (some syslog activity maybe, but not much more):

[  303.072983] EXT4-fs (mmcblk1p2): error count: 4
[  303.077558] EXT4-fs (mmcblk1p2): initial error at 1404216838: ext4_mb_generate_buddy:756
[  303.085690] EXT4-fs (mmcblk1p2): last error at 1404388969: ext4_mb_generate_buddy:757

What does that mean?

Best regards,

-- 
David Jander
Protonic Holland.