Re: ext4: journal has aborted

[Theodore Ts'o <tytso@mit.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.

Thanks!!

						- Ted