[Bug 85207] agd5f drm-next-3.19-wip + Unreal Elemental sometimes = list_add corruption/hung task

https://bugs.freedesktop.org/show_bug.cgi?id=85207

--- Comment #5 from Andy Furniss adf.lists@gmail.com --- (In reply to Christian König from comment #4)

Created attachment 108165 [details] [review] Possible fix

Ups! Forgotten to take the VM lock in radeon_gem_va_update_vm. Fix is attached.

Thanks for testing, Christian.

I don't know about Elemental as it's far harder to trigger, but first try with valley produced -

[ 156.617954] radeon 0000:01:00.0: GPU fault detected: 146 0x02e83504 [ 156.617960] radeon 0000:01:00.0: VM_CONTEXT1_PROTECTION_FAULT_ADDR 0x00010F17 [ 156.617961] radeon 0000:01:00.0: VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x08035004 [ 156.617963] VM fault (0x04, vmid 4) at page 69399, read from VGT (53)