Comment # 33 on bug 935086 from Uwe Geuder

(In reply to Takashi Iwai from comment #26)
> (In reply to Takashi Iwai from comment #25)
> > Could you add "noresume" boot option (while keeping "resume=xxx" option) and
> > retest for a few times whether you still get the unexpected reboot with
> > SLEEP_METHOD="kernel"?
> 
> I meant SLEEP_MODULE, of course.

If noresume is on the kernel cmd line and SLEEP_MODULE="kernel" the system does
not even hibernate (systemctl hibernate does nothing visible).

At least /usr/lib/pm-utils/sleep.d/99Zgrub seems to check for the noresume
option, I have not studied it details what happens if there is a match.