Re: generic/232 test failures on 4.14-rc1

Jan Kara
2017-09-27T09:42:06Z

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:
> > On Mon 25-09-17 15:59:46, Jan Kara wrote:
> > > On Thu 21-09-17 11:48:46, Eric Whitney wrote:
> > > > 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.
> > >
> > > > Example output from the failed test:
> > > >
> > > > QA output created by 232
> > > >
> > > > Testing fsstress
> > > >
> > > > seed = S
> > > > Comparing user usage
> > > > 218a219
> > > > > #3740 -- 4 0 0 1 0 0
> > > > 245a247
> > > > > #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.