Deadlock with crashdump

[lukemarsden]

I've started collecting kernel crashdumps and dmesg output of the ZoL deadlocks I'm able to reproduce:

http://hybridcluster.net/zol-hangs/201405060819/

This is now on Ubuntu 14.04, with kernel 3.13.0-24-generic #47-Ubuntu SMP, and the following zfs module info:

filename:       /lib/modules/3.13.0-24-generic/updates/dkms/zfs.ko
version:        0.6.2-2.1~trusty~13.gbp7d6f55
license:        CDDL
author:         Sun Microsystems/Oracle, Lawrence Livermore National Laboratory
description:    ZFS
srcversion:     8EAC8D11923CD437A7B0573

The machine was potentially running concurrent snapshot/destroy/mount/unmount operations at the time of the deadlock. Hopefully the crashdump will elucidate us.

[ryao]

I suspect that this was fixed by the synctask rewrite @ahrens did. It is in HEAD for the upcoming 0.6.3 release.

[lukemarsden]

I've upgraded to HEAD and I'm still seeing deadlocks, modinfo zfs:

filename:       /lib/modules/3.13.0-24-generic/extra/zfs/zfs/zfs.ko
version:        0.6.2-274_g2c33b91
license:        CDDL
author:         Sun Microsystems/Oracle, Lawrence Livermore National Laboratory
description:    ZFS
srcversion:     F6471B3005F520F80BF2AD5

Latest kernel crashdump: http://hybridcluster.net/zol-hangs/201405061448/

(Sorry, guess I didn't wait long enough for stacks to show up in the dmesg output before generating the crashdump - but it was definitely hung on zpool status).

[behlendorf]

This deadlock looks like the same root cause as #2301.

[behlendorf]

Closing as a duplicate of #2301 was has been resolved.