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

[Alper Nebi Yasak]

On 2024-12-11 01:32 +03:00, Andrea Bolognani wrote:
> 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.

Thanks for the explanation. Indeed, I can connect over ssh and run
`systemd-inhibit --what=shutdown --mode=delay sleep infinity` and get
the same behaviour, so it's definitely about the inhibit delay.

I guess the login screen showing up during the delay is a different bug
somewhere else, maybe in systemd/logind...?