Created attachment 134171 [details]
dmesg

I'm getting a 

[  404.518419] BUG: unable to handle kernel NULL pointer dereference at
0000000000000220
[  404.518445] IP: amdgpu_vm_bo_invalidate+0x71/0x150 [amdgpu]


when running vulkan cts with 32 processes (with tests that cause OOM removed).

Current linux tip:

commit 2dd9dc59c1419c090b084461165bd8b0adf1fecb (HEAD -> amd-staging-drm-next,
origin/amd-staging-drm-next)
Author: Harry Wentland <harry.wentland@amd.com>
Date:   Thu Aug 31 21:17:05 2017 -0400

    drm/amdgpu: Remove unused flip_flags from amdgpu_crtc


It doesn't seem like there is a correlating hang: the card is clocked down and
/sys/kernel/debug/dri/0/amdgpu_fence_info shows no pending fences. However,
eventually some of the CTS processes get stuck, and I can't kill them gdb into
them etc. Probably a pagefault that gets stuck, since fence waiting doesn't
seem to get stuck easily? Either way, not sure if that is related yet.

AFAICT the issue is that vm->root.base.bo is NULL in

if (evicted && bo->tbo.resv == vm->root.base.bo->tbo.resv) {