As a note, I know this is a new issue, and I can reproduce it by clicking around in menu items. I have not recently updated my mesa or xf86 driver, and this problem is now occurring consistently, and had not occurred previously.
Issue seems to have been fixed a while ago, so I am closing this issue.
ubuntu 16.04 r9 285
[15342.107078] amdgpu 0000:01:00.0: GPU fault detected: 146 0x0938c80c
[15342.107081] amdgpu 0000:01:00.0: VM_CONTEXT1_PROTECTION_FAULT_ADDR 0x00123927
[15342.107081] amdgpu 0000:01:00.0: VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x0A0C800C
[15342.107083] VM fault (0x0c, vmid 5) at page 1194279, read from 'TC3' (0x54433300) (200)
This indicates a hardware programming error in the radeon driver and should be reported to their bug tracker instead.
Nothing extracted yet.
Let me know if you would like the dump log from /tmp/dumps/assert_20150415000458_17.dmp