system hangs at reboot/shutdown

Rosika · 03-08-2019, 08:39 AM

Hi altogether,

after performing a clean install of Lubuntu 18.04.2 LTS, 64 bit, I experience shutdown/reboot problems. The system hangs at a specific point.

After deactivating plymouth ("noplymouth" instead of "quiet splash") I was able to find out where the system hangs.
The last entries are as follows:

Code:

systemd-shutdow [1]: 12 output lines suppressed due to rate limiting
systemd-shutdown [1]: Syncing filesytems and block devices
systemd-shutdown [1]: Sending SIGTERM to remaining processes
systemd-journald [284]: Received SIGTERM from PID 1 (systemd-shutdown)
systemd-shutdown [1]: Sendig SIKILL to remaining processes ...
systemd-shutdown [1]: Unmountig file systems
EXT4-fs (sdc1): re-mounted. Opts: block_validity,barrier,user-xattr,acl,errors=remount-ro
systemd-shutdown [1]: All filesystems unmounted
systemd-shutdown [1]: Deactivating swaps
systemd-shutdown [1]: All swaps deactivated
systemd-shutdown [1]: Deactivating loop devices
systemd-shutdown [1]: All loop devices detached
systemd-shutdown [1]: Detaching DM devices
kvm: exiting hardware virtualization

So the kvm thing seems to be the culprit.

Does anyone know what to do?

The whole thing is a bit odd as I have a pristine system and everything should work perfectly.

Greetings.
Rosika

business_kid · 03-08-2019, 09:08 AM

If you suspect kvm, don't start it or kill it before you shut down. If you have a VM or more running, kvm may be very unwilling to shut down. I have VB, and I have toi shut the VM before I can close stuff.

Also try killing kvm, and make sure it's dead.

Last some BIOS and kernel settings can prevent power down, and must be uid 0 to switch off.

Rosika · 03-08-2019, 09:16 AM

Hi business_kid,

thanks for your reply.

I haven´t started kvm - at least not to my knowledge. As I said It´s a pretty pristine system and I haven´t installed any VMs yet.

Code:

ps aux | grep kvm
rosika    4034  0.0  0.0  21536  1104 pts/2    S    16:09   0:00 grep --color=auto kvm

This is the only thing associated with kvm.

Quote:

Last some BIOS and kernel settings can prevent power down, and must be uid 0 to switch off.

I really don´t want to mess around with BIOS settings, but what about kernel settings? Yet I´m not sure how to manage that......

Greetings
Rosika

pan64 · 03-08-2019, 09:51 AM

your grep means [almost] nothing (there is no process named kvm). But still there can be a daemon related to kvm or something else (like kernel module).

hazel · 03-08-2019, 10:36 AM

There's a kernel module called kvm. To find out if this is loaded in your system, use lsmod.

If it is loaded, find out what is loading it and deactivate it. I'm pretty certain it's a systemd thing.

Rosika · 03-08-2019, 11:05 AM

Hi pan64 and hazel,

thanks.
lsmod gives me the following entries with kvm:

Code:


	Code:
	kvm_intel             212992  0
kvm                   598016  1 kvm_intel
irqbypass              16384  1 kvm

Quote:

If it is loaded, find out what is loading it and deactivate it.

Yet I´m not sure how to proceed.

pan64 · 03-08-2019, 11:19 AM

hm. try rmmod to remove and try to blacklist if you don't want to load it at boot-time.

Rosika · 03-08-2019, 11:32 AM

So like that:

Code:

sudo rmmod kvm_intel
sudo rmmod kvm

?

And what about irqbypass 16384 1 kvm?

hazel · 03-08-2019, 11:48 AM

That means that the irqbypass module uses kvm and depends on it. So if you blacklist kvm, irqbypass won't load either. But I don't think you actually need it if you're not running a virtual machine.

pan64 · 03-08-2019, 12:03 PM

yes, something like that (for rmmod)

RickDeckard · 03-08-2019, 06:11 PM

Type into /etc/modprobe.d/blacklist.conf:

blacklist kvm
blacklist kvm_intel
blacklist irqbypass

Then restart

Rosika · 03-09-2019, 11:47 AM

Thanks folks for your help.

I´ll try that and get back to you with the results.

Greetings.
Rosika

Rosika · 03-10-2019, 09:41 AM

Hi again,

in the meantime I tried the following:

Code:

rosika@rosika-Lenovo-H520e ~> lsmod | grep kvm
kvm_intel             212992  0
kvm                   598016  1 kvm_intel
irqbypass              16384  1 kvm

rosika@rosika-Lenovo-H520e ~> sudo modprobe -r kvm_intel

rosika@rosika-Lenovo-H520e ~> sudo modprobe -r kvm

That unloaded the respective modules and I tried to reboot.
But again it failed. The system hung up again. But this time at another point:

Code:

systemd-shutdown[1]: Detaching DM devices

Not sure how to proced now.

Greetings
Rosika

Rosika · 03-10-2019, 09:50 AM

The only solution which seems to work is using the terminal with

Code:

shutdown -H -P +0

or

Code:

shutdown -H -r +0

for reboot.
It seems like other people had the same problem and they came up with that one.

wladicus · 07-21-2020, 10:50 AM

I have also been having Reboot & Shutdown problems.
After trying many suggested solutions, I finally decided to boot
Ubuntu with the previous kernel LINUX 5.3.0-61-generic and now everything works great!
So, from my particular experience it is the new kernel release -62 that is the culprit.
I hope this helps some users.

I also noticed that WiFi is now recognized whereas with kernel -62 it completely disappeared.