Thanks Emil! Unfortunaltey I am not familiar with Optimus nor do I have
appropriate hardware.

Could someone provide a backtrace (with symbols) of the binary which ends up
saying "malloc: unknown:0: assertion botched", etc? Or maybe even Valgrind it?
Although that may be pretty advanced.

I don't think this commit is the actual culprit, but it is possible that the
failing binary uses UserPtr if it detects it, and has a bug in those optional
code paths.

Another interesting test would be to try non-working libdrm on a kernel without
UserPtr support.