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GPU Fault while rendering scenes with subsurface scattering using OpenCL
Closed, ResolvedPublic

Description

System Information
Operating system: Arch Linux, Ubuntu 18.04 LTS
Graphics card: Sapphire RX 590 Nitro+

Blender Version
Broken:
2.79 release (2c0c1f494dcf), 2.8 beta (266b1e2cdbc1)

Short description of error
I'm running arch linux, and recently I've got a new sapphire RX 590 Nitro+. On Arch Linux, I'm using an open source amdgpu driver, that's included in linux kernel, and opencl driver from amdgpu-pro package. On Ubuntu I'm using full official amdgpu-pro driver set.

On both occasions, rendering with OpenCL works fine, unless the scene contains objects with subsurface scattering (either subsurface scattering in principled BDSF, or a standalone node). In that case, after finishing OpenCL kernel compilation (which happens without any problems), my video output completely halts, and I have numerous "GPU fault" errors in my system journal (I've included full text as attachment in journalctl.txt). Blender terminal output doesn't produce any errors though.

At first, I thought it's a hardware or driver problem. I didn't find anything like this though. It only happens in blender, while trying to use subsurface node. Any other opencl uses (luxrender, phoronix test suite with juliagpu), as well as general benchmarks and stress tests of my graphics card are completely fine.

I tried using many combinations of older linux kernel versions (since it includes amdgpu driver) and related libraries (libdrm and amd opencl runtime). I also installed Ubuntu 18.04 and official proprietary amdgpu-pro driver set, but I had exactly the same problem, so I suspect it's a blender bug (and not related to my driver or kernel).

The problem doesn't occur if nodetree contains subsurface prior to opencl initialization, it's possible to make a new .blend, add principled bdsf and start rendering it, it will work until the first opencl kernel compilation, after which it crashes. On complex scenes though, it occurs anyway, even if I just opened the file and didn't change anything yet. There may be other cases when this problem occurs, but, unfortunately, trying to determine more causes is hard, since I need to hard-reset my computer every time.

I've tried various blender versions, including 2.77, 2.78, 2.79, latest stable 2.8 beta and latest nightly 2.8 build. On 2.77 and 2.78, it worked completely fine, due to missing opencl subsurface scattering implementation, and this shader was just black. On 2.79 and later, I experienced the problem described above.

I found a somewhat similar bug report, although it occurs in different conditions https://developer.blender.org/T57774.

I also included a "system-info.txt" file from my Arch Linux installation.

UPD: This bug was also reproduced on another system (arch linux) with Asus Strix r9 390 8G OC and amdgpu-pro opencl driver.

Exact steps for others to reproduce the error
Using opencl with amdgpu-pro driver, with included .blend file, for me, this problem can be reproduced by enabling "rendered" viewport mode first, and then adding some amount of subsurface scattering in principled BDSF node in node editor.