[Bug 1019347] Re: A message: "mount: / is busy" appears every time shutting down or rebooting.

[Gro-Tsen]

This bug report is highly confusing, so let me state this more clearly:
the plymouthd process is still running at the point where
/etc/init.d/umountroot is run in the shutdown process, and it is holding
some rw file descriptor stopping / from being remounted ro, thus causing
an unclean shutdown (and a longer boot time because the journal needs to
be replayed).

I don't know what plymouthd is supposed to be, but I'm pretty sure it
should be dead at that point in the shutdown process.  For some reason,
it is not responding to TERM signals: this should maybe be considered a
bug in plymouthd (notwithstanding the thought that plymouthd is a bug in
and of itself).

I didn't figure out what the offending rw file descriptor was.  I also
don't know why only certain users are affected (this is probably related
to the details in partitioning).

The obvious, but ugly, workaround is to edit /etc/init.d/umountroot to
add a line such as "/usr/bin/killall -9 plymouthd" at the top of the
do_stop() function (probably a good idea to add a couple of "sync"'s
around that, too).

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https://bugs.launchpad.net/bugs/1019347

Title:
  A message: "mount: / is busy" appears every time shutting down or
  rebooting.

Status in “upstart” package in Ubuntu:
  Confirmed

Bug description:
  I arrived here from bug 963106
  [https://bugs.launchpad.net/bugs/963106]. I thought that it was a
  problem with network-manager, but it was not.

  I was suggested that it is probably a problem with upstart : "that
  modemmanager simply hasn't had time to complete the shutdown process
  before umountroot is run. Since modemmanager is an upstart job,
  sendsigs doesn't kill it."

  lsb_release -rd:
       Description:	Ubuntu 12.04 LTS
       Release:	        12.04

  apt-cache policy upstart:
     upstart:
    Installed: 1.5-0ubuntu7
    Candidate: 1.5-0ubuntu7
    Version table:
   *** 1.5-0ubuntu7 0
          500 http://kambing.ui.ac.id/ubuntu/ precise-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       1.5-0ubuntu5 0
          500 http://kambing.ui.ac.id/ubuntu/ precise/main amd64 Packages

  Hope this will be fixed. Thanks.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: upstart 1.5-0ubuntu7
  ProcVersionSignature: Ubuntu 3.2.0-26.41-generic 3.2.19
  Uname: Linux 3.2.0-26-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.0.1-0ubuntu8
  Architecture: amd64
  Date: Sat Jun 30 00:08:18 2012
  InstallationMedia: Custom Live CD - Release amd64
  SourcePackage: upstart
  UpgradeStatus: No upgrade log present (probably fresh install)

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