Date:	Fri, 4 Jul 2014 11:40:31 +0200
From:	David Jander <david@...tonic.nl>
To:	Dmitry Monakhov <dmonakhov@...nvz.org>
Cc:	"Theodore Ts'o" <tytso@....edu>,
	Matteo Croce <technoboy85@...il.com>,
	"Darrick J. Wong" <darrick.wong@...cle.com>,
	linux-ext4@...r.kernel.org
Subject: Re: ext4: journal has aborted


Hi Dmitry,

On Thu, 03 Jul 2014 18:58:48 +0400
Dmitry Monakhov <dmonakhov@...nvz.org> wrote:

> On Thu, 3 Jul 2014 16:15:51 +0200, David Jander <david@...tonic.nl> wrote:
> > 
> > Hi Ted,
> > 
> > On Thu, 3 Jul 2014 09:43:38 -0400
> > "Theodore Ts'o" <tytso@....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@...cle.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?
> This means that it found previous error in internal ext4's log. Which is
> normal because your fs was corrupted before. It is reasonable to
> recreate filesystem from very beginning.
> 
> In order to understand whenever it is regression in eMMC driver it is
> reasonable to run integrity test for a device itself. You can run
> any integrity test you like, For example just run a fio's job
>  "fio disk-verify2.fio" (see attachment), IMPORTANT this script will
>  destroy data on test partition. If it failed with errors like
>  follows "verify: bad magic header XXX" than it is definitely a drivers issue.

I have been trying to run fio on my board with your configuration file, but I
am having problems, and since I am not familiar with fio at all, I can't
really figure out what's wrong. My eMMC device is only 916MiB in size, so I
edited the last part to be:

offset_increment=100M
size=100M

Is that ok?

I still get error messages complaining about blocksize though. Here is the
output I get (can't really make sense of it):

# ./fio ../disk-verify2.fio 
Multiple writers may overwrite blocks that belong to other jobs. This can cause verification failures.
/dev/mmcblk1p2: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=32
...
fio-2.1.10-49-gf302
Starting 4 processes
fio: blocksize too large for data set
fio: blocksize too large for data set
fio: blocksize too large for data set
fio: io_u.c:1315: __get_io_u: Assertion `io_u->flags & IO_U_F_FREE' failed.ta 00m:00s]
fio: pid=7612, got signal=6

/dev/mmcblk1p2: (groupid=0, jobs=1): err= 0: pid=7612: Fri Jul  4 09:31:15 2014
    lat (msec) : 4=0.19%, 10=0.19%, 20=0.19%, 50=0.85%, 100=1.23%
    lat (msec) : 250=56.01%, 500=37.18%, 750=1.14%
  cpu          : usr=0.00%, sys=0.00%, ctx=0, majf=0, minf=0
  IO depths    : 1=0.1%, 2=0.2%, 4=0.4%, 8=0.8%, 16=1.5%, 32=97.1%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued    : total=r=33/w=1024/d=0, short=r=0/w=0/d=0
     latency   : target=0, window=0, percentile=100.00%, depth=32

Run status group 0 (all jobs):

Disk stats (read/write):
  mmcblk1: ios=11/1025, merge=0/0, ticks=94/6671, in_queue=7121, util=96.12%
fio: file hash not empty on exit


This assertion bugs me. Is it due to the previous errors ("blocksize too large
for data set") or is is because my eMMC drive/kernel is seriously screwed?

Help please!

> If my theory is true and it is storage's driver issue than JBD complain
> simply because it do care about it's data (it does integrity checks).
> Can you also create btrfs on that partition and performs some io
> activity and run fsck after that. You likely will see similar corruption

Best regards,

-- 
David Jander
Protonic Holland.
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