Comment # 15 on bug 104762 from Fireball

I still experience this with mesa 18.0.0_rc3 and r600 driver.
Resolution first looked ok, user processes (plasmashell etc.) stopped crashing,
but screen locker and logout screen crash (not right away, after a few hours of
working).

As always, clearing caches in /root/.cache and /var/lib/sddm/.cache helps, but
this problem would occur again.
I use Qt 5.9.4.
Backtrace of /usr/lib64/libexec/ksmserver-logout-greeter mentions
/usr/lib64/dri/r600_dri.so.