Prevent cgroup filesystem from getting mounted

[Ivo Jimenez]

On trusty (14.04.1), I installed `cgroup-lite` (1.9) which mounts the virtual FS for cgroups subsystems in `/sys/fs/cgroup/*`. I've executed `cgclear` (from the `cgroup-bin` package) and uninstalled/purged `cgroup-lite`. When I reboot, the subsystems are mounted again. Question is: how can I prevent this from happening? Is there any config/script file that is read/executed when booting that accomplishes this?

No other packages related to cgroups (e.g. `lxc`, `libcgroup1` or `cgmanager`) are installed.

[Serge Hallyn (serge-hallyn)]

Assuming you are running upstart (the default init), can you show
the results of:

ls -l /etc/init
cat /etc/init/cgroup*
dpkg -S /etc/init/cg*

 status: incomplete
 importance: medium

[Ivo Jimenez (ivotron)]

this is what I get. thanks

ivo@optiplexona:~
$ ls -l /etc/init
total 440K
-rw-r--r-- 1 root root 320 Dec 8 2011 acpid.conf
-rw-r--r-- 1 root root 498 Jan 16 2014 alsa-restore.conf
-rw-r--r-- 1 root root 613 Jan 16 2014 alsa-state.conf
-rw-r--r-- 1 root root 487 Jan 16 2014 alsa-store.conf
-rw-r--r-- 1 root root 278 Jun 20 2010 anacron.conf
-rw-r--r-- 1 root root 1.6K Oct 1 2014 apport.conf
-rw-r--r-- 1 root root 261 Oct 25 2011 atd.conf
-rw-r--r-- 1 root root 207 Dec 30 2013 avahi-cups-reload.conf
-rw-r--r-- 1 root root 541 Oct 17 2011 avahi-daemon.conf
-rw-r--r-- 1 root root 1009 Mar 7 2012 bluetooth.conf
-rw-r--r-- 1 root root 328 Feb 21 2014 bootmisc.sh.conf
-rw-r--r-- 1 root root 232 Feb 21 2014 checkfs.sh.conf
-rw-r--r-- 1 root root 253 Feb 21 2014 checkroot-bootclean.sh.conf
-rw-r--r-- 1 root root 307 Feb 21 2014 checkroot.sh.conf
-rw-r--r-- 1 root root 266 Apr 26 2012 console.conf
-rw-r--r-- 1 root root 250 Oct 8 2012 console-font.conf
-rw-r--r-- 1 root root 509 Dec 21 2010 console-setup.conf
-rw-r--r-- 1 root root 1.1K Apr 26 2012 container-detect.conf
-rw-r--r-- 1 root root 356 Apr 26 2012 control-alt-delete.conf
-rw-r--r-- 1 root root 297 Jun 19 2012 cron.conf
-rw-r--r-- 1 root root 525 Jun 4 2014 cups-browsed.conf
-rw-r--r-- 1 root root 1.8K Sep 5 2014 cups.conf
-rw-r--r-- 1 root root 489 Nov 11 2013 dbus.conf
-rw-r--r-- 1 root root 273 Mar 30 2012 dmesg.conf
-rw-r--r-- 1 root root 1.5K Jun 18 10:14 docker.conf
-rw-r--r-- 1 root root 1003 Jun 19 2014 docker.io.conf
-rw-r--r-- 1 root root 1.4K Apr 26 2012 failsafe.conf
-rw-r--r-- 1 root root 380 Aug 30 2011 failsafe-x.conf
-rw-r--r-- 1 root root 267 Apr 26 2012 flush-early-job-log.conf
-rw-r--r-- 1 root root 1.3K Mar 14 2012 friendly-recovery.conf
-rw-r--r-- 1 root root 160 Sep 1 2014 gpu-manager.conf
-rw-r--r-- 1 root root 284 Jul 23 2013 hostname.conf
-rw-r--r-- 1 root root 557 Mar 29 2012 hwclock.conf
-rw-r--r-- 1 root root 444 Mar 29 2012 hwclock-save.conf
-rw-r--r-- 1 root root 131 Sep 28 2012 hybrid-gfx.conf
-rw-r--r-- 1 root root 579 Aug 26 2014 irqbalance.conf
-rw-r--r-- 1 root root 689 Apr 10 2014 kmod.conf
-rw-r--r-- 1 root root 2.4K Dec 5 2012 libvirt-bin.conf
-rw-r--r-- 1 root root 1.4K Apr 7 2014 lightdm.conf
-rw-r--r-- 1 root root 1.6K Jan 7 2015 lxc.conf
-rw-r--r-- 1 root root 462 Jan 7 2015 lxc-instance.conf
-rw-r--r-- 1 root root 4.3K Jan 7 2015 lxc-net.conf
-rw-r--r-- 1 root root 347 Feb 25 2014 modemmanager.conf
-rw-r--r-- 1 root root 367 Mar 18 2011 module-init-tools.conf
-rw-r--r-- 1 root root 268 Feb 21 2014 mountall-bootclean.sh.conf
-rw-r--r-- 1 root root 1.3K Feb 21 2014 mountall.conf
-rw-r--r-- 1 root root 349 Apr 12 2012 mountall-net.conf
-rw-r--r-- 1 root root 261 Apr 12 2012 mountall-reboot.conf
-rw-r--r-- 1 root root 311 Feb 21 2014 mountall.sh.conf
-rw-r--r-- 1 root root 1.2K Apr 12 2012 mountall-shell.conf
-rw-r--r-- 1 root root 327 Feb 21 2014 mountdevsubfs.sh.conf
-rw-r--r-- 1 root root 405 Apr 12 2012 mounted-debugfs.conf
-rw-r--r-- 1 root root 730 Feb 21 2014 mounted-dev.conf
-rw-r--r-- 1 root root 480 Apr 12 2012 mounted-proc.conf
-rw-r--r-- ...

[Serge Hallyn (serge-hallyn)]

I wonder whether docker could be mounting something. Could you
show the result of "grep cgroup /var/log/upstart/*" and
"sudo dmesg" ?

[Serge Hallyn (serge-hallyn)]

Yes, trusty's /etc/init/docker.io.conf has:

mount -t tmpfs -o uid=0,gid=0,mode=0755 cgroup /sys/fs/cgroup

[Ivo Jimenez (ivotron)]

that was it. thanks!