I tried to create a new virtual machine with similar settings today and shutdown via Proxmox worked.
The older virtual machine (created on 16/08) has exactly the same
package versions and running kernel and was unable to shutdown via
Proxmox until I reboot it today. Very strange.
So it seems that this may not be a issue with the kernel but with Proxmox.
Journal from Proxmox host before VM reboot:
Aug 22 16:33:10 sam qm[51346]: <root@pam> starting task
UPID:sam:0000C894:0239A288:5F412CA6:qmshutdown:106:root@pam:
Aug 22 16:33:10 sam qm[51348]: shutdown VM 106:
UPID:sam:0000C894:0239A288:5F412CA6:qmshutdown:106:root@pam:
Aug 22 16:34:00 sam systemd[1]: Starting Proxmox VE replication
runner...
-- Subject: A start job for unit pvesr.service has begun execution
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- A start job for unit pvesr.service has begun execution.
--
-- The job identifier is 358778.
Aug 22 16:34:01 sam systemd[1]: pvesr.service: Succeeded.
-- Subject: Unit succeeded
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- The unit pvesr.service has successfully entered the 'dead'
state.
Aug 22 16:34:01 sam systemd[1]: Started Proxmox VE replication
runner.
-- Subject: A start job for unit pvesr.service has finished
successfully
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- A start job for unit pvesr.service has finished successfully.
--
-- The job identifier is 358778.
Aug 22 16:34:57 sam qm[51348]: VM 106 qmp command failed -
received interrupt
Aug 22 16:34:57 sam qm[51348]: VM quit/powerdown failed
Aug 22 16:34:57 sam qm[51346]: <root@pam> end task
UPID:sam:0000C894:0239A288:5F412CA6:qmshutdown:106:root@pam: VM
quit/powerdown failed
After VM manual reboot:
Aug 22 16:36:27 sam sudo[54269]: pam_unix(sudo:session): session
opened for user root by erdnaxe(uid=0)
Aug 22 16:36:28 sam qm[54270]: <root@pam> starting task
UPID:sam:0000D400:0239F00C:5F412D6C:qmshutdown:106:root@pam:
Aug 22 16:36:28 sam qm[54272]: shutdown VM 106:
UPID:sam:0000D400:0239F00C:5F412D6C:qmshutdown:106:root@pam:
Aug 22 16:36:31 sam kernel: vmbr10: port 5(tap106i0) entered
disabled state
Aug 22 16:36:31 sam qm[54270]: <root@pam> end task
UPID:sam:0000D400:0239F00C:5F412D6C:qmshutdown:106:root@pam: OK
Aug 22 16:36:31 sam sudo[54269]: pam_unix(sudo:session): session
closed for user root
If the problem reappear I will try to collect more information to open an issue on Proxmox side or Debian side.
Sorry for the inconvenience,