[Bug 1444402] Re: LXC with r/w sys and udev keeps trying to unmount bind mounts

[Brian Murray]

Hello Iain, or anyone else affected,

Accepted systemd into vivid-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/systemd/219-7ubuntu6
in a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to
enable and use -proposed.  Your feedback will aid us getting this update
out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, and change the tag
from verification-needed to verification-done. If it does not fix the
bug for you, please add a comment stating that, and change the tag to
verification-failed.  In either case, details of your testing will help
us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: systemd (Ubuntu Vivid)
       Status: In Progress => Fix Committed

** Tags added: verification-needed

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Title:
  LXC with r/w sys and udev keeps trying to unmount bind mounts

Status in systemd:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Vivid:
  Fix Committed

Bug description:
  I recently hit ENOSPC which turned out to be the result of various
  syslogs from the current and previous boots totalling up to 30G.

  They were filled with messages like

  Apr 15 11:22:35 vivid systemd[1]: Unit var-lib-schroot-union-underlay-vivid\x2damd64\x2d5d4f7453\x2d9a95\x2d4a6a\x2d9aee\x2d9394923bf734.mount is bound to inactive unit dev-disk-by\x2duuid-980689ca\x2de7d9\x2d4a99\x2d8230\x2d33b8b6e917cd.device. Stopping, too.
  Apr 15 11:22:35 vivid systemd[1]: Unmounting /var/lib/schroot/union/underlay/vivid-amd64-5d4f7453-9a95-4a6a-9aee-9394923bf734...
  Apr 15 11:22:35 vivid umount[31795]: umount: /var/lib/schroot/union/underlay/vivid-amd64-5d4f7453-9a95-4a6a-9aee-9394923bf734: target is busy
  Apr 15 11:22:35 vivid umount[31795]: (In some cases useful info about processes that
  Apr 15 11:22:35 vivid umount[31795]: use the device is found by lsof(8) or fuser(1).)
  Apr 15 11:22:35 vivid systemd[1]: var-lib-schroot-union-underlay-vivid\x2damd64\x2d5d4f7453\x2d9a95\x2d4a6a\x2d9aee\x2d9394923bf734.mount mount process exited, code=exited status=32
  Apr 15 11:22:35 vivid systemd[1]: Failed unmounting /var/lib/schroot/union/underlay/vivid-amd64-5d4f7453-9a95-4a6a-9aee-9394923bf734.
  Apr 15 11:22:35 vivid systemd[1]: Unit var-lib-schroot-union-underlay-vivid\x2damd64\x2d5d4f7453\x2d9a95\x2d4a6a\x2d9aee\x2d9394923bf734.mount is bound to inactive unit dev-disk-by\x2duuid-980689ca\x2de7d9\x2d4a99\x2d8230\x2d33b8b6e917cd.device. Stopping, too.
  Apr 15 11:22:35 vivid systemd[1]: Unmounting /var/lib/schroot/union/underlay/vivid-amd64-5d4f7453-9a95-4a6a-9aee-9394923bf734...
  Apr 15 11:22:35 vivid systemd[1]: Unmounted /var/lib/schroot/union/underlay/vivid-amd64-5d4f7453-9a95-4a6a-9aee-9394923bf734.
  Apr 15 11:22:35 vivid systemd[1]: Unit var-lib-schroot-union-underlay-vivid\x2damd64\x2d5d4f7453\x2d9a95\x2d4a6a\x2d9aee\x2d9394923bf734.mount entered failed state.

  looping constantly for the duration of any builds in sbuild.

  Why is systemd trying to do this?

  SRU TEST CASE:
  --------------
   - Create a vivid container, and set "lxc.aa_profile = unconfined" and "lxc.mount.auto = sys:rw cgroup" in its config. (Note that the latter is not supported!)
   - Start the container
   - Run "mount -v -o bind /bin /mnt"
   - Observe that it doesn't stay mounted, but "sudo journalctl" says

  Mai 06 09:17:08 test systemd[1]: Unit mnt.mount is bound to inactive unit dev-sda3.device. Stopping, too.
  Mai 06 09:17:08 test systemd[1]: Unmounting /mnt...
  Mai 06 09:17:08 test systemd[1]: Unmounted /mnt.

   - With the fixed package bind mounts stay mounted.

  REGRESSION POTENTIAL: This could potentially break cleanup of stale
  mount points of either hotplug devices which disappear, or media which
  get forcefully ejected (like CDs). Testing should include that these
  still work.

  laney at vivid> apt-cache policy systemd
  systemd:
    Installed: 219-7ubuntu1
    Candidate: 219-7ubuntu1
    Version table:
   *** 219-7ubuntu1 0
          500 http://sherwood/ubuntu/ vivid/main amd64 Packages
          100 /var/lib/dpkg/status

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