Phi-2 requires a disabled autocast in attention layer
Author: gugarosa
Pull request: yes

# What does this PR do?

Phi-2 has an attention overflow issue, and since the model weights were released with a MIT license, there is no short-term solution in replacing them (re-training the model). Therefore, the only solution we could find to cover all corner cases regarding the overflow, is to also disable the autocast in the attention layer.

This update follows the current [model file](https://huggingface.co/microsoft/phi-2/blob/main/modeling_phi.py) we have on `microsoft/phi-2` repository. Additionally, it follows the [previous solution](https://huggingface.co/microsoft/phi-2/blob/834565c23f9b28b96ccbeabe614dd906b6db551a/modeling_phi.py#L347) we had done before the Phi integration.

Please let me know if we can think of any different solutions, or if there is anything else we can do.

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Comments:
Thanks for the PR! We are not super super fans of context managers for such things. TBH it's not that bad! cc @amyeroberts what's your take? 


Thanks for adding this fix @gugarosa! 

I don't mind this too much, it's pretty clean and simple :) Let's get @younesbelkada's opinion on whether this will break any other assumptions about weight loading in the library and possible alternatives

No problems, thanks everyone for looking at it! Hopefully this is a one-time behavior and we will never see it again on future models 🙏 

Hi @gugarosa , seems like we are still having loss issue: https://github.com/huggingface/transformers/issues/28488#issuecomment-1940449050

**Update**: Ignore my comment - Apparently, my new installation of transformers didn't with your changes so same loss curves are expected. I tried to rerun training with changes in your PR and training failed: 
```
  File "/home/minimalist/miniconda3/envs/axolotl_Feb12/lib/python3.9/site-packages/torch/nn/modules/module.py", line 1527, in _call_impl
    return forward_call(*args, **kwargs)
  File "/home/minimalist/miniconda3/envs/axolotl_Feb12/lib/python3.9/site-packages/torch/amp/autocast_mode.py", line 16, in decorate_autocast
    return func(*args, **kwargs)
  File "/home/minimalist/miniconda3/envs/axolotl_Feb12/lib/python3.9/site-packages/torch/amp/autocast_mode.py", line 16, in decorate_autocast
    return func(*args, **kwargs)
  File "/home/minimalist/work/projects/transformers/src/transformers/models/phi/modeling_phi.py", line 318, in forward
    query_states = self.q_proj(hidden_states)
  File "/home/minimalist/miniconda3/envs/axolotl_Feb12/lib/python3.9/site-packages/torch/nn/modules/module.py", line 1518, in _wrapped_call_impl
    return self._call_impl(*args, **kwargs)
  File "/home/minimalist/miniconda3/envs/axolotl_Feb12/lib/python3.9/site-packages/torch/nn/modules/module.py", line 1527, in _call_impl
    return forward_call(*args, **kwargs)
  File "/home/minimalist/miniconda3/envs/axolotl_Feb12/lib/python3.9/site-packages/torch/nn/modules/linear.py", line 114, in forward
    return F.linear(input, self.weight, self.bias)
RuntimeError: mat1 and mat2 must have the same dtype, but got Float and BFloat16
```

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.

Sorry for the extremely delayed response.

Sounds good, I will update the documentation.