Fixed base model class name extraction from PeftModels
diff --git a/src/transformers/trainer.py b/src/transformers/trainer.py
index ad3b840385dbe..7af4532492697 100755
--- a/src/transformers/trainer.py
+++ b/src/transformers/trainer.py
@@ -646,7 +646,7 @@ def _activate_neftune(self, model):
         unwrapped_model = unwrap_model(model)
 
         if is_peft_available() and isinstance(unwrapped_model, PeftModel):
-            embeddings = unwrapped_model.base_model.get_input_embeddings()
+            embeddings = unwrapped_model.base_model.model.get_input_embeddings()
         else:
             embeddings = unwrapped_model.get_input_embeddings()
 
@@ -667,7 +667,7 @@ def _deactivate_neftune(self, model):
         unwrapped_model = unwrap_model(model)
 
         if is_peft_available() and isinstance(unwrapped_model, PeftModel):
-            embeddings = unwrapped_model.base_model.get_input_embeddings()
+            embeddings = unwrapped_model.base_model.model.get_input_embeddings()
         else:
             embeddings = unwrapped_model.get_input_embeddings()
 
@@ -2752,10 +2752,11 @@ def compute_loss(self, model, inputs, return_outputs=False):
             self._past = outputs[self.args.past_index]
 
         if labels is not None:
-            if is_peft_available() and isinstance(model, PeftModel):
-                model_name = unwrap_model(model.base_model)._get_name()
+            unwrapped_model = unwrap_model(model)
+            if is_peft_available() and isinstance(unwrapped_model, PeftModel):
+                model_name = unwrapped_model.base_model.model._get_name()
             else:
-                model_name = unwrap_model(model)._get_name()
+                model_name = unwrapped_model._get_name()
             if model_name in MODEL_FOR_CAUSAL_LM_MAPPING_NAMES.values():
                 loss = self.label_smoother(outputs, labels, shift_labels=True)
             else:

# What does this PR do?

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Fixes #27161


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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      Pull Request section?
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- [ ] Did you write any new necessary tests?


## Who can review?

@pacman100, @muellerzr 

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Models:

- text models: @ArthurZucker and @younesbelkada
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- graph models: @clefourrier

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- generate: @gante
- pipelines: @Narsil
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- tokenizers: @ArthurZucker
- trainer: @muellerzr and @pacman100

Integrations:

- deepspeed: HF Trainer/Accelerate: @pacman100
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- Big Model Inference: @SunMarc
- quantization (bitsandbytes, autogpt): @SunMarc and @younesbelkada

Documentation: @stevhliu and @MKhalusova

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- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

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- TensorFlow: @Rocketknight1

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