It seems that there's a bug (race condiiton) in the kernel's CPUFreq code, only discovered from 4.20 due to some changes in the kernel.
I understand it is still an issue in the 5.0 kernel. (read it somewhere but now I just cannot find the link ...)

See:
https://bugzilla.kernel.org/show_bug.cgi?id=199349#c4

I happen to have a shutdown hang issue with my rig and was wondering if the fact that I have cpufrequtils installed makes things worse.
It is set at 'performance' with no min o max settings so that it does not kick in (I guess it does not).

But the issue is still there. =-/

Would uninstalling cpufrequtils and using linux-cpupower instead for setting performance help in any way?

Is all this (cpufreq and linux-cpupower) in any way related to cpuidle and how it works?

groucho@devuan:~$ sudo dmesg | grep -i cpuidle
[    0.172005] cpuidle: using governor ladder
[    0.188005] cpuidle: using governor menu
groucho@devuan:~$ 

Thanks in advance.

A.