Comment # 82 on bug 1105271 from Borislav Petkov

Good work, thanks!

This explains it all, lemme see if I can write it correctly:

tsc_init() enables the __use_tsc static key on the BSP and *that* grabs
jump_label_mutex before it grabs the hotplug lock while on another CPU
the CPU notifier runs which holds the hotplug lock already and then
enables another static key - the sched_smt_present - which causes the
lock inversion by trying to grab the jump_label_mutex first.

@jikos: the way I see it, there's no way around backporting the jump
label patches so that we don't grab that hotplug again in the notifier
call.

Or am I missing something?