RuntimeError: CUDA unknown error - this may be due to an incorrectly set up environment, e.g. changing env variable CUDA_VISIBLE_DEVICES

I am trying to check the GPU device name but after executing this code. I got this unknown runtime error. please help me to solve this problem and give complete instructions to solve this error. Thanks.





        (base) kumar@kumar:~$ conda activate pytorch
        (pytorch) kumar@kumar:~$ python
        Python 3.8.5 (default, Sep  4 2020, 07:30:14) 
        [GCC 7.3.0] :: Anaconda, Inc. on linux
        Type "help", "copyright", "credits" or "license" for more information.
        >>> import torch
        >>> print(torch.__version__)
        1.9.0a0+gitb39eeb0
        >>> print(torch.version.cuda)
        11.2
        >>> print(torch.cuda.current_device())
        Traceback (most recent call last):
          File "<stdin>", line 1, in <module>
          File "/home/kumar/anaconda3/envs/pytorch/lib/python3.8/site-packages/torch/cuda/__init__.py", line 430, in current_device
            _lazy_init()
          File "/home/kumar/anaconda3/envs/pytorch/lib/python3.8/site-packages/torch/cuda/__init__.py", line 170, in _lazy_init
            torch._C._cuda_init()
        RuntimeError: CUDA unknown error - this may be due to an incorrectly set up environment, e.g. changing env variable CUDA_VISIBLE_DEVICES after program start. Setting the available devices to be zero.
        >>> exit()
        

Here is the output of nvcc -V

  (pytorch) kumar@kumar:~$ nvcc -V
    nvcc: NVIDIA (R) Cuda compiler driver
    Copyright (c) 2005-2021 NVIDIA Corporation
    Built on Sun_Feb_14_21:12:58_PST_2021
    Cuda compilation tools, release 11.2, V11.2.152
    Build cuda_11.2.r11.2/compiler.29618528_0
    (pytorch) kumar@kumar:~$ 

here is the output of nvidia-smi

    Thu Apr  8 15:04:49 2021       
    +-----------------------------------------------------------------------------+
    | NVIDIA-SMI 460.67       Driver Version: 460.39       CUDA Version: 11.2     |
    |-------------------------------+----------------------+----------------------+
    | GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
    | Fan  Temp  Perf  Pwr: Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
    |                               |                      |               MIG M. |
    |===============================+======================+======================|
    |   0  GeForce RTX 3070    Off  | 00000000:01:00.0  On |                  N/A |
    |  0%   38C    P8    10W / 220W |    525MiB /  7982MiB |      0%      Default |
    |                               |                      |                  N/A |
    +-------------------------------+----------------------+----------------------+
                                                                                   
    +-----------------------------------------------------------------------------+
    | Processes:                                                                  |
    |  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
    |        ID   ID                                                   Usage      |
    |=============================================================================|
    |    0   N/A  N/A      1015      G   /usr/lib/xorg/Xorg                 70MiB |
    |    0   N/A  N/A      1542      G   /usr/lib/xorg/Xorg                257MiB |
    |    0   N/A  N/A      1675      G   /usr/bin/gnome-shell               89MiB |
    |    0   N/A  N/A      3560      G   ...AAAAAAAAA= --shared-files       94MiB |
    +-----------------------------------------------------------------------------+
        

However, when I try to run

print(torch.cuda.current_device())

I get the following error:

Traceback (most recent call last):
              File "<stdin>", line 1, in <module>
              File "/home/kumar/anaconda3/envs/pytorch/lib/python3.8/site-packages/torch/cuda/__init__.py", line 430, in current_device
                _lazy_init()
              File "/home/kumar/anaconda3/envs/pytorch/lib/python3.8/site-packages/torch/cuda/__init__.py", line 170, in _lazy_init
                torch._C._cuda_init()
            RuntimeError: CUDA unknown error - this may be due to an incorrectly set up environment, e.g. changing env variable CUDA_VISIBLE_DEVICES after program start. Setting the available devices to be zero.