I just updated to .11 and I think the api for calling torch.nn.DataParallel has changed. In the previous version if I only had one GPU I would call the function with None passed as the device_ids. Now if I pass None I get the following error:
  File "/home/jtremblay/anaconda2/envs/py3/lib/python3.6/site-packages/torch/nn/parallel/data_parallel.py", line 96, in data_parallel
    output_device = device_ids[0]
TypeError: 'NoneType' object is not subscriptable

documentation link to the function: http://pytorch.org/docs/nn.html?highlight=parallel#torch.nn.DataParallel 20