Kubuntu 15.04, kernel 4.0rc3, amd hd7850 with recent (from ppa oibaf) open
source drivers. Dolphin emulator runs fine except that I have a complete freeze
when I exit. I have to reboot the computer (although it seems to be still
running as I can remotely log with ssh). I tried under kde,  then under icewm,
to see if it was the compositor's fault. No change. Windowed or fullscreen:
same freeze. I tried to stop Dolphin with the interface buttons: same freeze.

kubuntu 15.04, i7 4770k non overclocked, amd hd7850 on open source drivers.

dmesg log is here:
http://pastebin.ca/2962286

I reported the bug to the Dolphin team. Told me that "Basically it's AMD's
GL_AMD_pinned_memory extension causing a kernel hardlock." and that I have to
report here.