group.of.nepali.translators team mailing list archive

[Louis Bouchard <louis.bouchard@xxxxxxxxxxxxx>]

Targetting Zesty as the fix will come after release so as a SRU.

** Also affects: unattended-upgrades (Ubuntu Zesty)
   Importance: High
     Assignee: Louis Bouchard (louis-bouchard)
       Status: In Progress

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https://bugs.launchpad.net/bugs/1654600

Title:
  unattended-upgrade-shutdown hangs when /var is a separate filesystem

Status in unattended-upgrades package in Ubuntu:
  In Progress
Status in unattended-upgrades source package in Xenial:
  Triaged
Status in unattended-upgrades source package in Yakkety:
  Triaged
Status in unattended-upgrades source package in Zesty:
  In Progress
Status in unattended-upgrades package in Debian:
  New

Bug description:
  [SRU justification]
  This fix is needed to make sure that the system does not hang on shutdown when /var is a speparate file system

  [Impact]
  System can hang up to 10 minutes if not fixed.

  [Fix]
  Change the systemd unit's ExecStart to an ExecStop so the unit is correctly sequenced.

  [Test Case]
  In a VM with /var separated from the / file system, shutdown the VM. It will hang for 10 minutes

  [Regression]
  None to be expected. A ExecStop unit will be sequenced before the Before= units which is earlier than previously.

  [Original description of the problem]
  The systemd unit file unattended-upgrades.service is used to stop a running unattended-upgrade
  process during shutdown. This unit file is running together with all filesystem
  unmount services.

  The unattended-upgrades service checks if the lockfile for unattended-upgrade
  (in /var/run) exists, and if it does, there is an unattended-upgrade in progress
  and the service will wait until it finishes (and therefore automatically wait at
  shutdown).

  However, if /var is a separate filesystem, it will get unmounted even though /var/run
  is a tmpfs that's still mounted on top of the /var/run directory in the /var filesystem.
  The unattended-upgrade script will fail to find lockfile, sleeps for 5 seconds, and
  tries to check the lockfile again. After 10 minutes (the default timeout), it will finally
  exit and the system will continue shutdown.

  The problem is the error handling in /usr/share/unattended-upgrades/unattended-upgrade-shutdown
  where it tries to lock itself:

      while True:
          res = apt_pkg.get_lock(options.lock_file)
          logging.debug("get_lock returned %i" % res)
          # exit here if there is no lock
          if res > 0:
              logging.debug("lock not taken")
              break
          lock_was_taken = True

  The function apt_pkg.get_lock() either returns a file descriptor, or -1 on an error.
  File descriptors are just C file descriptors, so they are always positive integers.
  The code should check the result to be negative, not positive. I have attached a patch
  to reverse the logic.

  Additional information:

  1)
  Description:	Ubuntu 16.04.1 LTS
  Release:	16.04

  2)
  unattended-upgrades:
    Installed: 0.90ubuntu0.3
    Candidate: 0.90ubuntu0.3
    Version table:
   *** 0.90ubuntu0.3 500
          500 http://nl.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
          500 http://nl.archive.ubuntu.com/ubuntu xenial-updates/main i386 Packages
          100 /var/lib/dpkg/status
       0.90 500
          500 http://nl.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
          500 http://nl.archive.ubuntu.com/ubuntu xenial/main i386 Packages
  3)
  Fast reboot
  4)
  Very slow reboot (after a 10 minutes timeout)

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