Fairscale integration not working for me
🐛 Bug
When I try to train a model with Fairscale (ddp_sharded), I get this error always:
  File "/home/ubuntu/anaconda3/envs/torch/lib/python3.7/site-packages/fairscale/nn/data_parallel/sharded_ddp.py", line 500, in _setup_backward_hooks
    assert p_tmp.grad_fn is not None
AssertionError
Could anyone please point me at an example I could run?

PyTorch Version (e.g., 1.0): 1.8
OS (e.g., Linux): Ubuntu 18.04
How you installed PyTorch (conda, pip, source): conda install -c pytorch pytorch
Build command you used (if compiling from source):
Python version: 3.7
CUDA/cuDNN version: 10.2
GPU models and configuration: 8xV100
Any other relevant information: