Only one distro/OS can access CUDA at a time

[Kyle2142]

Environment

Windows build number: 10.0.20152.0
Your Distribution version: Debian 9.12 and Ubuntu 18.04
Whether the issue is on WSL 2 and/or WSL 1: 2

Steps to reproduce

1. Install two WSL2 distros
2. Follow setup for Nvidia CUDA usage
3. Open a shell for each
4. Try use Nvidia CUDA in both

Alternatively, try use CUDA on windows after starting a distro

Expected behavior

Expected CUDA to work in both, or documentation about this limitation

Actual behavior

CUDA fails on anything but the first one to try use it

Comments

I first encountered this due to having Debian but then Nvidia requires Ubuntu for CUDA in WSL.
Not sure how this person knew, but this comment says only the first distro will have access.
Today I found this also applies to windows, as my Killing Floor 2 game which uses CUDA for Nvidia Flex crashed as soon as it tried to use CUDA (debian was running in the background). wsl --shutdown made me able to continue playing without further hassle.
Snippet from KF2 logs, showing this.

[0522.19] DevFlex: Flex: CUDA error: 77. at ../../../flex.cu:5375
[0530.54] Log: === Critical error: ===
Fatal error!
Address = 0xd057d1d8 (filename not found) [in D:\Steam\steamapps\common\killingfloor2\Binaries\Win64\flexExtRelease_x64.dll]
Address = 0xd057e6e0 (filename not found) [in D:\Steam\steamapps\common\killingfloor2\Binaries\Win64\flexExtRelease_x64.dll]
Address = 0xd057bb13 (filename not found) [in D:\Steam\steamapps\common\killingfloor2\Binaries\Win64\flexExtRelease_x64.dll]
...

As I do not know whether this is a problem in WSL or on Nvidia's side, I've created posts on both.

[onomatopellan]

For WSL2 happens because of #5506. Fix is coming.

For Windows the Nvidia team need to answer on their forum.

[benhillis]

/dupe #5506

[ghost]

Hi! We've identified this issue as a duplicate of another one that already exists in this repository. This specific instance is being closed in favor of tracking the concern over on the referenced thread.

Thanks for your report!