linux 4.17.0-7.8 ADT test failure with linux 4.17.0-7.8

[Thadeu Lima de Souza Cascardo]

Testing failed on:
    i386: https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-cosmic/cosmic/i386/l/linux/20180810_012246_01e82@/log.gz

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1786462

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Colin Ian King (colin-king)]

When running this test on 3 concurrent VMs with this kernel this runs fine. With the ZFS backing store of the VMs set to sync on writes, I can slow the I/O and I get a lot of timeout issues which result in tests running for a long time and probably would get nuked by the testing infrastructure -
see attached dmesg log for the timeouts.

I am currently speculating that the tests are failing because VFAT is sub-optimal compared to other file systems and with a slow backing store we may be just getting lockup warnings because of slow I/O write out and/or syncs.

At least I have a reproducer. I don't think this is a critical show stopping bug. I will try and figure out what particular stress case is causing the issue, but this may take a while to iterate through.

[Colin Ian King (colin-king)]

Potential fix applied: http://kernel.ubuntu.com/git/ubuntu/autotest-client-tests.git/commit/?id=cf7f9e75bb1fe0f7d798a8d49e0407b602017848

[Colin Ian King (colin-king)]

Any update? Does this fix the issue?

[Po-Hsu Lin (cypressyew)]

The ubuntu_vfat_stress test has completed on a Cosmic i386 bare-metal node without any issue
Linux pepe 4.17.0-7-generic #8-Ubuntu SMP Fri Aug 3 15:54:53 UTC 2018 i686 i686 i686 GNU/Linux

Test log here: https://pastebin.ubuntu.com/p/dcjbMyhhp6/

Thanks!!