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Fix batched generation for prompts of different lengths (#2216)

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* fix ignoring of attention mask after prefill stage in decoding

* update naming to avoid confusion

---------

Co-authored-by: Неизвестный Пользователь722497 <dolegosmirnov@sberbank.ru>
This commit is contained in:
RunFMe 2025-06-02 13:59:10 +03:00 • committed by GitHub
commit d80e8a5cd8
1 changed files with 30 additions and 3 deletions
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33
unsloth/models/llama.py
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@ -99,7 +99,7 @@ torch_nn_functional_softmax = torch.nn.functional.softmax
SDPA_HAS_GQA = "enable_gqa" in scaled_dot_product_attention.__doc__
# Fix new HF's inference code
def _fast_prepare_inputs_for_generation(self, input_ids, **kwargs,):
def _fast_prepare_inputs_for_generation(self, input_ids, attention_mask=None, **kwargs,):
past_key_values = kwargs.get("past_key_values", None)
if past_key_values is not None:
# Check for uninitialized DynamicCache
@ -107,11 +107,38 @@ def _fast_prepare_inputs_for_generation(self, input_ids, **kwargs,):
past_key_values = None
kwargs["past_key_values"] = None
else:
bs, cache_length = input_ids.shape
input_ids = input_ids[:,[-1]]
kwargs["attention_mask"] = kwargs["attention_mask"][:,[-1]]
# Get to the base model
base_model = self
if hasattr(base_model, 'base_model_prefix'):
base_model = getattr(base_model, base_model.base_model_prefix)
if hasattr(base_model, "_prepare_4d_causal_attention_mask_with_cache_position"):
attention_mask = base_model._prepare_4d_causal_attention_mask_with_cache_position(
attention_mask,
sequence_length=1,
target_length=cache_length,
dtype=self.dtype,
device=input_ids.device,
cache_position=torch.arange(cache_length, cache_length+1, device=input_ids.device),
batch_size=bs,
config=self.config,
past_key_values=past_key_values,
)
else:
attention_mask = attention_mask[:,[-1]]
logger.warning_once(
f"{self.__class__.__name__} has no `_prepare_4d_causal_attention_mask_with_cache_position` method "
"defined in its base modeling class. Compiled forward passes will be sub-optimal. If you're "
"writing code, see Llama for an example implementation. If you're a user, please report this "
"issue on GitHub."
)
if "cache_position" in kwargs:
kwargs["position_ids"] = kwargs["cache_position"]
return { "input_ids" : input_ids, **kwargs, }
return { "input_ids" : input_ids, "attention_mask": attention_mask, **kwargs, }
pass