Hi Darrick!

On Tue 26-09-17 18:19:29, Darrick J. Wong wrote:

On Tue, Sep 26, 2017 at 02:58:31PM +0200, Jan Kara wrote:

quoted

On Mon 25-09-17 15:59:46, Jan Kara wrote:

quoted

On Thu 21-09-17 11:48:46, Eric Whitney wrote:

quoted

I'm seeing generic/232 fail from time to time when running a 4.14-rc1 kernel
on xfstest-bld's most recent kvm-xfstests test appliance.  In one set of
trials, it failed in the same manner 4 out of 10 times when running the 4k test
configuration for ext4.

The failure bisects to "quota: Do not acquire dqio_sem for dquot overwrites in
v2 format" (ab2b86360f6e).  When this patch was reverted in a 4.14-rc1 kernel,
the failure did not reoccur in a series of 20 trials.

Thanks for debugging this! I'd just note that the commit hash of that
change is different for me - d2faa415166b2883428efa92f451774ef44373ac.

quoted

Example output from the failed test:

QA output created by 232

Testing fsstress

seed = S
Comparing user usage
218a219

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#3740     --       4       0       0              1     0     0       

245a247

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#45       --       0       0       0              1     0     0     

Note:  I'm also seeing a similar failure for generic/233, but the patch
containing the root cause likely comes somewhere after ab2b86360f6e.  I'll post
another bug report once I locate it.

I'll try to debug this further. Thanks for report!

Attached patch fixes the problem for me. I'll merge it through my tree.

Ever since 4.14-rc1, I've noticed the same problem (intermittent
failures of generic/{232,233,270}) that Eric Whitney was complaining
about when running xfstests against XFS.  I'll try a proper bisect
tomorrow, but given the big locking rework I wonder if that rings any
bells for you?

Hum, no idea. XFS uses its own thing for quotas so my changes don't
influence it at all. I don't know much about XFS internal quota
implementation so I don't have a good guess what could have caused the
breakage you see. I'm sorry.

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR