[Bug 1594658] Re: diskless setup with nfs mounted home hangs on shutdown/reboot

[Darko Veberic]

this appears also on all our desktops in the institute after an upgrade
from 14.04 to 16.04. user yp homes are mounted via autofs/am through nfs
and the network is setup via dhcp.

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Title:
  diskless setup with nfs mounted home hangs on shutdown/reboot

Status in nfs-utils package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  Ubuntu 16.04 fresh install hangs when shutting down.
  The system is diskless PXE-booted with a couple of nfs mounted directories including homedir.

  As I have no persistent storage whatsoever, I don't have any logs, but
  in debug-shell, running journalctl -f I can see that it hangs at

  [   *] (1 of 2) A stop job running for Raise Network Interfaces (10s / 1min 30s)Jun 20 20:23:05 $hostname kernel: nfs: server $nfs-ip-address not responding, still trying
  Jun 20 20:23:05 $hostname kernel: nfs: server $nfs-ip-address not responding, still trying
  Jun 20 20:23:14 $hostname kernel: nfs: server $nfs-ip-address not responding, still trying
  Jun 20 20:24:08 $hostname kernel: nfs: server $nfs-ip-address not responding, still trying

  Second job in "(1 of 2)" is thermald, turning it off does not fix the problem.
  Also, this counter "(10s / 1min 30s)" stops visually updating.

  server $nfs-ip-address is not responding, because, all network
  interfaces are already down at this point.

  I am not exactly sure why this happens. Looks like there is a wrong
  ordering of shutdown of systemd services, which bring down interfaces
  before something nfs-related, but I am not sure if that's the reason
  of hanging.

  
  Workaround that fixes the problem:
  In /lib/systemd/system/networking.service
  comment following line:
  ExecStop=/sbin/ifdown -a --read-environment

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