I was able to record an ApiTrace which shows the problem consistently. However,
it's 2.5 gigabytes and contains personal information I'd rather not share on a
public bugtracker -- I think a trace can only be truncated, removing stuff from
the beginning messes up the OpenGL context?

I cannot switch to the virtual console when the freeze is triggered.

I also built radeonsi from current Mesa git
(9b9a89cd795fda462a6ee898ef6e5135ca79d94e) but the problem persisted.