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Since last week shutdown has stopped working in my system. Either i use the shutdown menu in Unity/LightDM or use sudo shutdown -h now the system just locks, and i can't either use Alt+reisub. Only a hard shutdown works.

If i shutdown from a tty, this is the last output i get before the system freezes:

umount: /run/lock: not munted
umount: /run/shm: not mounted
mount: / is busy
* Will now halt
[...] Power down.

After this the disk usage led turns on and i can't do anything else.

What could be the problem?

What i have tried

  • set acpi=force in GRUB doesn't help;
  • check for errors in the shutdown process: i get any error at all during shutdown, except the lines stated on top;
  • acpid is installed.
  • reboot/suspend works just fine!


As seen here i get some warnings regarding ACPI in /var/log/boot.log.

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mount: / is busy... what? You sure you didn't install any packages that might have interfered with the shutdown? – MiJyn Nov 28 '12 at 21:07
yes i have, but are all packages that should have nothing with the shutdown process: latex, vala, text editors, etc. Maybe the problem was originated by some update? I will try booting with other kernel – Salem Nov 28 '12 at 21:19
Also run the system updates again :) – MiJyn Nov 28 '12 at 21:19
up vote 4 down vote accepted

The problem is a bug, and it is caused by no just one service, but a set of these, see this tread for further information.

Most likely dnsmasq, dhclient, modem-manager and network-manager are the involved services.

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Simple solution that worked for me

Before shutting down, click on network icon on the top system tray and uncheck "Enable Networking".

PS. I'm a linux noob. Discovered this trick from this thread.

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