How to ruin Linus's vacation

No, it's not related. That bug has to do - as far as I can tell right now - with lockdep noticing there's recursive locking going on but not being told that this is a case of expected nested locking. Well, I think the nesting is expected ...

Anyhow, the message lockdep prints, includes the neat line:
*** DEADLOCK ***

It took me a few days before I noticed that the kernel actually still was running quite OK after that disturbing message.

By the way, the reason you ran into this recently seems to be that systemd-30 is (apparently) the first program in wide use that triggers this.