Commit 4a4ff66dbe radeonsi: also prefetch compute shaders enabled prefetching
the compute shader to TC L2 for CIK+. This causes GPU VM errors on Hawaii,
Kabini, and likely other CIK GPUs when running certain OpenCL programs (it
seems that the key is to call clCreateContext() twice or more, see below) with
Clover, both with amdgpu and radeon kernel drivers. I have tested with

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc.
[AMD/ATI] Hawaii XT GL [FirePro W9100] [1002:67a0]

on Fedora rawhide (28) with kernel 4.15.0-0.rc7.git2.1.fc28.x86_64.

I'll minimize the example program that causes this (right now using GROMACS
tests, but that's unnecessarily complex), and provide the details (grepped +
full dmesg) in the comments for both amdgpu and radeon kernel drivers.