[Pkg-libvirt-maintainers] Bug#1089607: Bug#1089607: libvirt-daemon: Virtual networks cause login screen to show up while system is shutting down

[Andrea Bolognani]

On Mon, Dec 09, 2024 at 11:08:37PM +0300, Alper Nebi Yasak wrote:
> Hello,
> 
> I've been having this weird issue for a while. When I try to shut down
> my computer from a desktop environment, I get logged out and see the GDM
> (or LightDM) login screen for about twenty seconds before the system
> continues shutting down. This is a bit confusing/annoying, I can even
> log in during this time but the computer will shutdown anyway.
> 
> After downgrading various packages and tinkering a bit, I've managed to
> track it down to libvirt networks. Workarounds I found that fix the problem:
> 
> - `virsh -c qemu:///system net-destroy default`, or
> - `systemctl disable --now libvirtd.service`, or
> - Downgrade to 10.8.0-1 (< 10.9.0-1)
> 
> I didn't have time to figure out what interacts with what, but I guess
> some weirdness including systemd services? libvirtd.service stays
> running during the twenty seconds and stopping it continues shutdown
> immediately.
> 
> I use virt-manager for some VMs, so I have set up a default virtual
> network to start at boot. Apparently libvirtd.service is supposed to
> shut down when nothing is connected (`--timeout 120`), and the virtual
> network prevents this.

Correct. The timeout will not kick in  as long as there are running
domains or active networks, so effectively libvirtd will be up at all
times.

This is somewhat mitigated on a split daemons deployment, where only
virtnetworkd needs to stay up, but unfortunately we don't have split
daemons in Debian yet.

> So it keeps running until shutdown, and then
> delays the shutdown, making the display manager show up?
> 
> Attaching a `journalctl -b` output, not sure what other logs could help.
> I kind of spent too much time on figuring this much out, I hope it's
> enough for you to reproduce.

Thanks for taking the time to look into the issue and report it.

We already have an ticket tracking this upstream:

  https://gitlab.com/libvirt/libvirt/-/issues/695

It looks like the fix might be tricky. Hopefully it can be sorted out
before trixie. I'll make sure that upstream doesn't forget about it,
since it disproportionately affects Debian.

The reason for that is this file:

  $ cat /usr/lib/systemd/logind.conf.d/unattended-upgrades-logind-maxdelay.conf
  [Login]
  # delay
  InhibitDelayMaxSec=30

This overrides the default systemd delay and results in the pause
between when the shutdown is initiated and when it actually happens
to be 30s instead of just 5s.

In other words, uninstalling the unattended-upgrades packages is an
effective workaround to apply while you wait for the issue to receive
a proper fix.

-- 
Andrea Bolognani <eof at kiyuko.org>
Resistance is futile, you will be garbage collected.
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