这个问题是由选错GPU编号导致，改成正确的就好。

问题

RuntimeError: CUDA error: invalid device ordinal
CUDA kernel errors might be asynchronously reported at some other API call, so the stacktrace below might be incorrect.
For debugging consider passing CUDA_LAUNCH_BLOCKING=1.
Compile with `TORCH_USE_CUDA_DSA` to enable device-side assertions.

解决办法

"cuda:2"改成"cuda:0"

参考资料

CUDA error: invalid device ordinal when using python 3.9