[Bug 1551415] Re: systemctl stop networking hang / timeout

[Stefan Bader]

That sounds like it is related. While doing more debug I found that
network-manager starts dhclient in forground mode (-d) and that is not
affected by bug 1551351. But regardless of how it was started, dhclient
seem not to react on SIGHUP. Maybe disconnecting from the network
manually uses a more aggressive method of stopping the dhclient than
just doing a shutdown or reboot. The system probably goes into the mode
of first trying to send SIGHUP to running processes, then wait a bit and
finally doing a SIGTERM. That would explain the increased time.

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https://bugs.launchpad.net/bugs/1551415

Title:
  systemctl stop networking hang / timeout

Status in ifupdown package in Ubuntu:
  Confirmed

Bug description:
  I noticed today on lxd that the latest xenial image is failing to bring down networking
  $ cat /etc/cloud/build.info
    build_name: server
    serial: 20160227-141431

  to reproduce:

  $ lxd-images import ubuntu --alias xenial xenial --stream=daily
  $ lxc launch xenial xtest
  # wait a bit
  $ lxc exec xtest /bin/bash

  % systemctl stop networking
  ... long time passes ....

  % systemctl status networking
  ● networking.service - Raise network interfaces
     Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled)
    Drop-In: /run/systemd/generator/networking.service.d
             └─50-insserv.conf-$network.conf
     Active: failed (Result: timeout) since Mon 2016-02-29 20:28:14 UTC; 5s ago
       Docs: man:interfaces(5)
    Process: 1241 ExecStop=/sbin/ifdown -a --read-environment (code=exited, status=0/SUCCESS)
    Process: 951 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=0/SUCCESS)
    Process: 948 ExecStartPre=/bin/sh -c [ "$CONFIGURE_INTERFACES" != "no" ] && [ -n "$(ifquery --read-environme
   Main PID: 951 (code=exited, status=0/SUCCESS)

  Feb 29 20:26:35 xtest dhclient[992]: DHCPOFFER of 10.0.3.238 from 10.0.3.1
  Feb 29 20:26:35 xtest dhclient[992]: DHCPACK of 10.0.3.238 from 10.0.3.1
  Feb 29 20:26:35 xtest ifup[951]: DHCPACK of 10.0.3.238 from 10.0.3.1
  Feb 29 20:26:35 xtest ifup[951]: bound to 10.0.3.238 -- renewal in 1669 seconds.
  Feb 29 20:26:35 xtest systemd[1]: Started Raise network interfaces.
  Feb 29 20:26:44 xtest systemd[1]: Stopping Raise network interfaces...
  Feb 29 20:28:14 xtest systemd[1]: networking.service: State 'stop-sigterm' timed out. Killing.
  Feb 29 20:28:14 xtest systemd[1]: Stopped Raise network interfaces.
  Feb 29 20:28:14 xtest systemd[1]: networking.service: Unit entered failed state.
  Feb 29 20:28:14 xtest systemd[1]: networking.service: Failed with result 'timeout'.
  root at xtest:~# ubuntu-bug /lib/systemd/system/networking.service

  Related bugs:
   * bug 1551351:  dhclient does not renew leases

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: ifupdown 0.8.10ubuntu1
  ProcVersionSignature: Ubuntu 4.4.0-8.23-generic 4.4.2
  Uname: Linux 4.4.0-8-generic x86_64
  ApportVersion: 2.20-0ubuntu3
  Architecture: amd64
  Date: Mon Feb 29 20:28:28 2016
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
  SourcePackage: ifupdown
  UpgradeStatus: No upgrade log present (probably fresh install)

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