Crash remediation
Sometimes folk (me included) have had crashes upon attempted shutdown.
The screen is filled with call trace output & needs a hard poweroff (by holding down power button until turns off).
Cause is usually an incompatible kernel module.
The crash output should have a line starting with RIP: & listing the module name at end of that line.
Two particularly problematic modules in kernels after 5.8 are snd_hda_codec_idt and snd_hda_codec_realtek.
Probable fix options are:
1. Use a kernel before 5.9 series (could need even earlier)
2. Use a kernel that does not have the offending module(s) set
3. blacklist the module, via the kernel (or linux) command line in the .cfg file (grub.cfg, syslinux.cfg etc), thus:
- append kernel or linux line with (example only): modprobe.blacklist=modulename1,modulename2 . . .
4. blacklist the module(s) via entry in /etc/modprobe.d/blacklist.conf
No guarantees that the module isn't required - if so, option 1 best.