Christophe Leroy [off-list ref] writes:
Le 20/09/2021 à 15:55, Nathan Lynch a écrit :
quoted
If, due to bugs elsewhere, we get into unregister_cpu_online() with a CPU
that isn't marked hotpluggable, we can emit a warning and return an
appropriate error instead of crashing.
Is it only a bug situation, or is it something that can happen in real
life ?
If it can happen in real life, kernels with panic_on_warn will still be
impacted.
I only found this by inspection, and it can happen only due to a bug in
CPU device registration at boot. The flag must not be set if the
platform or CPU can't support going offline.