This has been an issue since I bought my Palit Gamerock 5090, though I don’t reboot my PC often so it’s not that inconvenient. Right after the reboot sequence finishes, there are messages like watchdog: watchdog0: watchdog did not stop! and then there’s a “No signal” message on the monitor, no actual reboot happens. Same with shutdown. I waited for 10 minutes, nothing happens. Still, the kernel responds to REISUB which is how I have to reboot. The same effect happens if I unload nvidia_drm, no signal and the system seems to be frozen except REISUB still works. Could be red herring of course. I updated my BIOS (UEFI), I also tried with a stock Debian kernel, same exact issue. In the bug report I use a custom kernel with slightly adjusted options for desktop workloads.
Bug report file:
nvidia-bug-report.log.gz (1.9 MB)