On booting my system I get a kernel panic claiming about "Unexpected reschedule of offline CPU#0". From what I remember it targeted to a smp.c at line 128 with the function native_smp_send_reschedule. I don't know which exact kernel version this is but on the last working version "cat /proc/version_signature" shows "Ubuntu 4.13.0-15.16-generic 4.13.4" and the kernel panic happened with the 4.13.x version Ubuntu provided after this version (so maybe it is 4.13.5 or such).
This issue also happened with version 4.14.x and in version 4.15.x I still get a kernel panic at boot but this time I did see a tick-broadcast.c at line 644 being involved.