flash-attention is not running, although is_flash_attn_2_available() returns true
Author: 6sixteen
Pull request: no

### System Info

- `transformers` version: 4.40.1
- Platform: Windows-10-10.0.22631-SP0
- Python version: 3.11.9
- Huggingface_hub version: 0.22.2
- Safetensors version: 0.4.3
- Accelerate version: 0.29.3
- Accelerate config:    not found
- PyTorch version (GPU?): 2.3.0+cu121 (True)
- Tensorflow version (GPU?): not installed (NA)
- Flax version (CPU?/GPU?/TPU?): not installed (NA)
- Jax version: not installed
- JaxLib version: not installed
- Using GPU in script?: <fill in>
- Using distributed or parallel set-up in script?: <fill in>

### Who can help?
@Narsil
_No response_

### Information

- [x] The official example scripts
- [ ] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

1.  I pip flash-attention through [https://github.com/bdashore3/flash-attention/releases](url)， which provides compiled package for windows.  And is_flash_attn_2_available() returns true.
2.  I run the comfyui workflow [https://github.com/ZHO-ZHO-ZHO/ComfyUI-Phi-3-mini](url), which runs the pipeline of model microsoft/Phi-3-mini-4k-instruct .
3. I received "You are not running the flash-attention implementation, expect numerical differences." 
4. I try to search this message in transformers, but find nothing （Unbelievable！！**This is the first question**）.  Then I clone the newest code from github，and I find this message in **modeling_phi3.py class Phi3Attention(nn.Module)**. And I find the transformers installed by pip is different between the transformers in github. The latter have a phi3 folder in model folder. So I try to build transformer by running python setup.py install , but i received 
error: [Errno 2] No such file or directory: 'c:\\users\\79314\\anaconda3\\envs\\comfyuitest\\lib\\site-packages\\transformers-4.41.0.dev0py3.11.egg\\transformers\\models\\deprecated\\trajectory_transformer\\__pycache__\\**convert_trajectory_transformer_original_pytorch_checkpoint_to_pytorch.cpython-311.pyc.1368162759184**'
5. I try my best to use the flash-attention, but I failed. 

### Expected behavior

How to run with flash-attention？
My curiosity：
Is there another reason limiting flash-attention，except is_flash_attn_2_available() 
Why I can't find "You are not running the flash-attention implementation, expect numerical differences." Which file contains these message?
How can I build the latest transformers?


Comments:
cc @ArthurZucker @Rocketknight1 

Yeah, so the PR to integrate Phi-3 with transformers has already been merged [here](https://github.com/huggingface/transformers/pull/30423). There hasn't been a stable release yet, which is why there's a difference between the pip version and when you install directly from source. So, you have to do the latter for now.

That being said, I also see the message `You are not running the flash-attention implementation, expect numerical differences.` pop up & it seems like this is the first LOC in the forward func, although I do not understand what this message means myself. 

Maybe @gugarosa can help, since this was his PR.

Hi!
Might be out of topic, but I'm also trying to install the flash-attn package to run the Phi-3 model.
I've run into an issue trying to installl the flash-attn package from its github repo with the following "python setup.py install".

I get a lot of warning like the one below, it does not crash but it does not seem to ever finish as well. Has anyone ran into something similar and was able to solve it?

(I'm using a cuda with version 12.1 and pytorch 2.3)

"/usr/local/cuda-12/include/cusparse.h:254:20: note: declared here
  254 | struct pruneInfo* pruneInfo_t CUSPARSE_DEPRECATED_TYPE;
      |                    ^~~~~~~~~~~
/usr/local/cuda-12/include/cusparse.h:4868:366: warning: 'pruneInfo_t' is deprecated: The type will be removed in the next major release [-Wdeprecated-declarations]
 4868 | cusparseSpruneCsr2csrByPercentage(cusparseHandle_t         handle,
      |                                                                                                                                                                                                                                                                                                                                                                              ^
/usr/local/cuda-12/include/cusparse.h:254:20: note: declared here
  254 | struct pruneInfo* pruneInfo_t CUSPARSE_DEPRECATED_TYPE;
      |                    ^~~~~~~~~~~
/usr/local/cuda-12/include/cusparse.h:4886:368: warning: 'pruneInfo_t' is deprecated: The type will be removed in the next major release [-Wdeprecated-declarations]
 4886 | cusparseDpruneCsr2csrByPercentage(cusparseHandle_t         handle,
      |                                                                                                                                                                                                                                                                                                                                                                                ^
/usr/local/cuda-12/include/cusparse.h:254:20: note: declared here
  254 | struct pruneInfo* pruneInfo_t CUSPARSE_DEPRECATED_TYPE;"

i am trying to use Phi-3-128k model, getting this problem

.modeling_phi3:You are not running the flash-attention implementation, expect numerical differences.
Killed

has anyone faced this error. How to solve this

Works fine after telling the pipeline which attention mechanism to use. I don't think there is a problem with Transformers lib:

```
!pip install transformers
!pip install flash-attn

from transformers import AutoModelForCausalLM
from transformers.utils import is_flash_attn_2_available

model = AutoModelForCausalLM.from_pretrained(
    "microsoft/Phi-3-mini-128k-instruct",
    device_map="cuda",
    torch_dtype="auto",
    trust_remote_code=True,
    attn_implementation="flash_attention_2"
)

is_flash_attn_2_available()
# True
```


i still sometimes get the same issue and also CUDA is out of memory issue.

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