Perhaps it's related to some other bug, but I don't have the other problems mentioned there and couldn't find such output: [ 20.875768] upowerd[2467] trap int3 ip:7f168f0886b7 sp:7fff48adce40 several lines like that are infrequently re-appearing in dmesg. downgrading to polkit-0.105 made that disappear.
That's not exactly spam... I've noticed these messages too, and when I wanted to configure power profiles, there was only 1 generic profile, and no suspend or hibernate options. Downgrading polkit to 0.105 fixed that as well.
upowerd failing is actually a symptom of polkit not being able to start. *** This bug has been marked as a duplicate of bug 420269 ***