Awesome! I tried the batch method you’ve described, and the following warning was returned:
/anaconda3/lib/python3.6/site-packages/torch/nn/modules/loss.py:431: UserWarning: Using a target size (torch.Size([1])) that is different to the input size (torch.Size([5931640])). This will likely lead to incorrect results due to broadcasting. Please ensure they have the same size.
  return F.mse_loss(input, target, reduction=self.reduction)

However, the code hasn’t thrown an error (yet) so maybe all is well.