Torch.cuda.is_available() returns False

nvcc–version shows Cuda compilation tools, release 9.1, V9.1.85
cat /usr/local/cuda/version.txt shows CUDA Version 10.1.168

when i try to install torch with cuda using conda install pytorch torchvision cuda90 -c pytorch

torch.cuda.is_available() returns False.

When i try to install cuda toolkit 10.1.168 using sudo sh is gives :
ERROR: An NVIDIA kernel module ‘nvidia-drm’ appears to already be loaded in your kernel. This may be because it is in use (for example, by an X server, a CUDA program, or the NVIDIA Persistence Daemon), but this may also happen if your kernel was configured without support for module unloading. Please be sure to exit any programs that may be using the GPU(s) before attempting to u
[INFO]: pgrade your driver. If no GPU-based programs are running, you know that your kernel supports module unloading, and you still receive this message, then an error may have occured that has corrupted an NVIDIA kernel module’s usage count, for which the simplest remedy is to reboot your computer.

looking into the logs it shows:

modprobe: FATAL: Module nvidia_drm is in use.

Please help regarding the above issue as i need use torch with cuda