Repository: huggingface/transformers
Pull request: Fix GPT2 with cross attention

# What does this PR do?

Fixes https://github.com/huggingface/transformers/issues/39746

Changed files:
filename: src/transformers/models/decision_transformer/modeling_decision_transformer.py
patch: @@ -268,53 +268,62 @@ def forward(
         **kwargs,
     ) -> tuple[Union[torch.Tensor, tuple[torch.Tensor]], ...]:
         is_cross_attention = encoder_hidden_states is not None
+        if past_key_value is not None:
+            if isinstance(past_key_value, EncoderDecoderCache):
+                is_updated = past_key_value.is_updated.get(self.layer_idx)
+                if is_cross_attention:
+                    # after the first generated id, we can subsequently re-use all key/value_layer from cache
+                    curr_past_key_value = past_key_value.cross_attention_cache
+                else:
+                    curr_past_key_value = past_key_value.self_attention_cache
+            else:
+                curr_past_key_value = past_key_value
+
         if is_cross_attention:
             if not hasattr(self, "q_attn"):
                 raise ValueError(
                     "If class is used as cross attention, the weights `q_attn` have to be defined. "
                     "Please make sure to instantiate class with `DecisionTransformerGPT2Attention(..., is_cross_attention=True)`."
                 )
-
             query_states = self.q_attn(hidden_states)
-            key_states, value_states = self.c_attn(encoder_hidden_states).split(self.split_size, dim=2)
             attention_mask = encoder_attention_mask
+
+            # Try to get key/value states from cache if possible
+            if past_key_value is not None and is_updated:
+                key_states = curr_past_key_value.layers[self.layer_idx].keys
+                value_states = curr_past_key_value.layers[self.layer_idx].values
+            else:
+                key_states, value_states = self.c_attn(encoder_hidden_states).split(self.split_size, dim=2)
+                shape_kv = (*key_states.shape[:-1], -1, self.head_dim)
+                key_states = key_states.view(shape_kv).transpose(1, 2)
+                value_states = value_states.view(shape_kv).transpose(1, 2)
         else:
             query_states, key_states, value_states = self.c_attn(hidden_states).split(self.split_size, dim=2)
+            shape_kv = (*key_states.shape[:-1], -1, self.head_dim)
+            key_states = key_states.view(shape_kv).transpose(1, 2)
+            value_states = value_states.view(shape_kv).transpose(1, 2)
 
         shape_q = (*query_states.shape[:-1], -1, self.head_dim)
-        shape_kv = (*key_states.shape[:-1], -1, self.head_dim)
-
         query_states = query_states.view(shape_q).transpose(1, 2)
-        key_states = key_states.view(shape_kv).transpose(1, 2)
-        value_states = value_states.view(shape_kv).transpose(1, 2)
 
-        if past_key_value is not None:
-            if isinstance(past_key_value, EncoderDecoderCache):
-                if is_cross_attention:
-                    past_key_value = past_key_value.cross_attention_cache
-                else:
-                    past_key_value = past_key_value.self_attention_cache
-            cache_kwargs = {"cache_position": cache_position}
-            key_states, value_states = past_key_value.update(
-                key_states, value_states, self.layer_idx, cache_kwargs=cache_kwargs
+        if (past_key_value is not None and not is_cross_attention) or (
+            past_key_value is not None and is_cross_attention and not is_updated
+        ):
+            # save all key/value_layer to cache to be re-used for fast auto-regressive generation
+            cache_position = cache_position if not is_cross_attention else None
+            key_states, value_states = curr_past_key_value.update(
+                key_states, value_states, self.layer_idx, {"cache_position": cache_position}
             )
+            # set flag that curr layer for cross-attn is already updated so we can re-use in subsequent calls
+            if is_cross_attention:
+                past_key_value.is_updated[self.layer_idx] = True
 
         is_causal = attention_mask is None and query_states.shape[-2] > 1 and not is_cross_attention
 
         using_eager = self.config._attn_implementation == "eager"
         attention_interface: Callable = eager_attention_forward
         if self.config._attn_implementation != "eager":
-            if self.config._attn_implementation == "sdpa" and (output_attentions or head_mask is not None):
-                using_eager = True
-                logger.warning_once(
-                    "`torch.nn.functional.scaled_dot_product_attention` does not support `output_attentions=True`. Falling back to "
-                    'eager attention. This warning can be removed using the argument `attn_implementation="eager"` when loading the model.'
-                )
-            else:
-                # Attention functions are consistent with previous equivalent attention classes, however they do not support some options
-                # (e.g. layer scaling, head mask) that eager supports. These implementations are thus equivalent to previous code, but
-                # not necessarily to eager (if mentioned options are provided).
-                attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]
+            attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]
 
         if using_eager and self.reorder_and_upcast_attn:
             attn_output, attn_weights = self._upcast_and_reordered_attn(

filename: src/transformers/models/gpt2/modeling_gpt2.py
patch: @@ -27,9 +27,10 @@
 from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss
 
 from ...activations import ACT2FN, get_activation
-from ...cache_utils import Cache, DynamicCache, EncoderDecoderCache, StaticCache
+from ...cache_utils import Cache, DynamicCache, EncoderDecoderCache
 from ...generation import GenerationMixin
-from ...modeling_attn_mask_utils import AttentionMaskConverter, _prepare_4d_attention_mask_for_sdpa
+from ...masking_utils import create_causal_mask
+from ...modeling_attn_mask_utils import _prepare_4d_attention_mask_for_sdpa
 from ...modeling_layers import GradientCheckpointingLayer
 from ...modeling_outputs import (
     BaseModelOutputWithPastAndCrossAttentions,
@@ -278,53 +279,62 @@ def forward(
         **kwargs,
     ) -> tuple[Union[torch.Tensor, tuple[torch.Tensor]], ...]:
         is_cross_attention = encoder_hidden_states is not None
+        if past_key_value is not None:
+            if isinstance(past_key_value, EncoderDecoderCache):
+                is_updated = past_key_value.is_updated.get(self.layer_idx)
+                if is_cross_attention:
+                    # after the first generated id, we can subsequently re-use all key/value_layer from cache
+                    curr_past_key_value = past_key_value.cross_attention_cache
+                else:
+                    curr_past_key_value = past_key_value.self_attention_cache
+            else:
+                curr_past_key_value = past_key_value
+
         if is_cross_attention:
             if not hasattr(self, "q_attn"):
                 raise ValueError(
                     "If class is used as cross attention, the weights `q_attn` have to be defined. "
                     "Please make sure to instantiate class with `GPT2Attention(..., is_cross_attention=True)`."
                 )
-
             query_states = self.q_attn(hidden_states)
-            key_states, value_states = self.c_attn(encoder_hidden_states).split(self.split_size, dim=2)
             attention_mask = encoder_attention_mask
+
+            # Try to get key/value states from cache if possible
+            if past_key_value is not None and is_updated:
+                key_states = curr_past_key_value.layers[self.layer_idx].keys
+                value_states = curr_past_key_value.layers[self.layer_idx].values
+            else:
+                key_states, value_states = self.c_attn(encoder_hidden_states).split(self.split_size, dim=2)
+                shape_kv = (*key_states.shape[:-1], -1, self.head_dim)
+                key_states = key_states.view(shape_kv).transpose(1, 2)
+                value_states = value_states.view(shape_kv).transpose(1, 2)
         else:
             query_states, key_states, value_states = self.c_attn(hidden_states).split(self.split_size, dim=2)
+            shape_kv = (*key_states.shape[:-1], -1, self.head_dim)
+            key_states = key_states.view(shape_kv).transpose(1, 2)
+            value_states = value_states.view(shape_kv).transpose(1, 2)
 
         shape_q = (*query_states.shape[:-1], -1, self.head_dim)
-        shape_kv = (*key_states.shape[:-1], -1, self.head_dim)
-
         query_states = query_states.view(shape_q).transpose(1, 2)
-        key_states = key_states.view(shape_kv).transpose(1, 2)
-        value_states = value_states.view(shape_kv).transpose(1, 2)
 
-        if past_key_value is not None:
-            if isinstance(past_key_value, EncoderDecoderCache):
-                if is_cross_attention:
-                    past_key_value = past_key_value.cross_attention_cache
-                else:
-                    past_key_value = past_key_value.self_attention_cache
-            cache_kwargs = {"cache_position": cache_position}
-            key_states, value_states = past_key_value.update(
-                key_states, value_states, self.layer_idx, cache_kwargs=cache_kwargs
+        if (past_key_value is not None and not is_cross_attention) or (
+            past_key_value is not None and is_cross_attention and not is_updated
+        ):
+            # save all key/value_layer to cache to be re-used for fast auto-regressive generation
+            cache_position = cache_position if not is_cross_attention else None
+            key_states, value_states = curr_past_key_value.update(
+                key_states, value_states, self.layer_idx, {"cache_position": cache_position}
             )
+            # set flag that curr layer for cross-attn is already updated so we can re-use in subsequent calls
+            if is_cross_attention:
+                past_key_value.is_updated[self.layer_idx] = True
 
         is_causal = attention_mask is None and query_states.shape[-2] > 1 and not is_cross_attention
 
         using_eager = self.config._attn_implementation == "eager"
         attention_interface: Callable = eager_attention_forward
         if self.config._attn_implementation != "eager":
-            if self.config._attn_implementation == "sdpa" and (output_attentions or head_mask is not None):
-                using_eager = True
-                logger.warning_once(
-                    "`torch.nn.functional.scaled_dot_product_attention` does not support `output_attentions=True`. Falling back to "
-                    'eager attention. This warning can be removed using the argument `attn_implementation="eager"` when loading the model.'
-                )
-            else:
-                # Attention functions are consistent with previous equivalent attention classes, however they do not support some options
-                # (e.g. layer scaling, head mask) that eager supports. These implementations are thus equivalent to previous code, but
-                # not necessarily to eager (if mentioned options are provided).
-                attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]
+            attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]
 
         if using_eager and self.reorder_and_upcast_attn:
             attn_output, attn_weights = self._upcast_and_reordered_attn(
@@ -861,8 +871,14 @@ def forward(
         # ._update_causal_mask() and ._prepare_4d_causal_attention_mask_with_cache_position() copied from LlamaModel
         if attention_mask is not None and attention_mask.ndim < 4:
             attention_mask = attention_mask.view(batch_size, -1)
-        causal_mask = self._update_causal_mask(
-            attention_mask, inputs_embeds, cache_position, past_key_values, output_attentions
+
+        causal_mask = create_causal_mask(
+            config=self.config,
+            input_embeds=inputs_embeds,
+            attention_mask=attention_mask,
+            cache_position=cache_position,
+            past_key_values=past_key_values,
+            position_ids=position_ids,
         )
 
         # If a 2D or 3D attention mask is provided for the cross-attention
@@ -903,9 +919,6 @@ def forward(
             # Model parallel
             if self.model_parallel:
                 torch.cuda.set_device(hidden_states.device)
-                # Ensure that attention_mask is always on the same device as hidden_states
-                if attention_mask is not None:
-                    attention_mask = attention_mask.to(hidden_states.device)
                 if isinstance(head_mask, torch.Tensor):
                     head_mask = head_mask.to(hidden_states.device)
             if output_hidden_states:
@@ -966,123 +979,6 @@ def forward(
             cross_attentions=all_cross_attentions,
         )
 
-    def _update_causal_mask(
-        self,
-        attention_mask: torch.Tensor,
-        input_tensor: torch.Tensor,
-        cache_position: torch.Tensor,
-        past_key_values: Cache,
-        output_attentions: bool,
-    ):
-        if self.config._attn_implementation == "flash_attention_2":
-            if attention_mask is not None and 0.0 in attention_mask:
-                return attention_mask
-            return None
-
-        # For SDPA, when possible, we will rely on its `is_causal` argument instead of its `attn_mask` argument, in
-        # order to dispatch on Flash Attention 2. This feature is not compatible with static cache, as SDPA will fail
-        # to infer the attention mask.
-        past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
-        using_static_cache = isinstance(past_key_values, StaticCache)
-
-        # When output attentions is True, sdpa implementation's forward method calls the eager implementation's forward
-        if self.config._attn_implementation == "sdpa" and not using_static_cache and not output_attentions:
-            if AttentionMaskConverter._ignore_causal_mask_sdpa(
-                attention_mask,
-                inputs_embeds=input_tensor,
-                past_key_values_length=past_seen_tokens,
-                is_training=self.training,
-            ):
-                return None
-
-        dtype = input_tensor.dtype
-        sequence_length = input_tensor.shape[1]
-        if using_static_cache:
-            target_length = past_key_values.get_max_cache_shape()
-        else:
-            target_length = (
-                attention_mask.shape[-1]
-                if isinstance(attention_mask, torch.Tensor)
-                else past_seen_tokens + sequence_length + 1
-            )
-
-        # In case the provided `attention` mask is 2D, we generate a causal mask here (4D).
-        causal_mask = self._prepare_4d_causal_attention_mask_with_cache_position(
-            attention_mask,
-            sequence_length=sequence_length,
-            target_length=target_length,
-            dtype=dtype,
-            cache_position=cache_position,
-            batch_size=input_tensor.shape[0],
-        )
-
-        if (
-            self.config._attn_implementation == "sdpa"
-            and attention_mask is not None
-            and attention_mask.device.type == "cuda"
-            and not output_attentions
-        ):
-            # Attend to all tokens in fully masked rows in the causal_mask, for example the relevant first rows when
-            # using left padding. This is required by F.scaled_dot_product_attention memory-efficient attention path.
-            # Details: https://github.com/pytorch/pytorch/issues/110213
-            min_dtype = torch.finfo(dtype).min
-            causal_mask = AttentionMaskConverter._unmask_unattended(causal_mask, min_dtype)
-
-        return causal_mask
-
-    @staticmethod
-    def _prepare_4d_causal_attention_mask_with_cache_position(
-        attention_mask: torch.Tensor,
-        sequence_length: int,
-        target_length: int,
-        dtype: torch.dtype,
-        cache_position: torch.Tensor,
-        batch_size: int,
-        **kwargs,
-    ):
-        """
-        Creates a causal 4D mask of shape `(batch_size, 1, query_length, key_value_length)` from a 2D mask of shape
-        `(batch_size, key_value_length)`, or if the input `attention_mask` is already 4D, do nothing.
-
-        Args:
-            attention_mask (`torch.Tensor`):
-                A 2D attention mask of shape `(batch_size, key_value_length)` or a 4D attention mask of shape
-                `(batch_size, 1, query_length, key_value_length)`.
-            sequence_length (`int`):
-                The sequence length being processed.
-            target_length (`int`):
-                The target length: when generating with static cache, the mask should be as long as the static cache,
-                to account for the 0 padding, the part of the cache that is not filled yet.
-            dtype (`torch.dtype`):
-                The dtype to use for the 4D attention mask.
-            cache_position (`torch.Tensor`):
-                Indices depicting the position of the input sequence tokens in the sequence.
-            batch_size (`torch.Tensor`):
-                Batch size.
-        """
-        if attention_mask is not None and attention_mask.dim() == 4:
-            # In this case we assume that the mask comes already in inverted form and requires no inversion or slicing.
-            causal_mask = attention_mask
-        else:
-            min_dtype = torch.finfo(dtype).min
-            causal_mask = torch.full(
-                (sequence_length, target_length), fill_value=min_dtype, dtype=dtype, device=cache_position.device
-            )
-            if sequence_length != 1:
-                causal_mask = torch.triu(causal_mask, diagonal=1)
-            causal_mask *= torch.arange(target_length, device=cache_position.device) > cache_position.reshape(-1, 1)
-            causal_mask = causal_mask[None, None, :, :].expand(batch_size, 1, -1, -1)
-            if attention_mask is not None:
-                causal_mask = causal_mask.clone()  # copy to contiguous memory for in-place edit
-                mask_length = attention_mask.shape[-1]
-                padding_mask = causal_mask[:, :, :, :mask_length] + attention_mask[:, None, None, :]
-                padding_mask = padding_mask == 0
-                causal_mask[:, :, :, :mask_length] = causal_mask[:, :, :, :mask_length].masked_fill(
-                    padding_mask, min_dtype
-                )
-
-        return causal_mask
-
 
 @auto_docstring(
     custom_intro="""

filename: src/transformers/models/vision_encoder_decoder/modeling_vision_encoder_decoder.py
patch: @@ -449,6 +449,7 @@ def forward(
         output_attentions: Optional[bool] = None,
         output_hidden_states: Optional[bool] = None,
         return_dict: Optional[bool] = None,
+        cache_position: Optional[torch.LongTensor] = None,
         **kwargs,
     ) -> Union[tuple[torch.FloatTensor], Seq2SeqLMOutput]:
         r"""
@@ -561,6 +562,7 @@ def forward(
             use_cache=use_cache,
             past_key_values=past_key_values,
             return_dict=return_dict,
+            cache_position=cache_position,
             **kwargs_decoder,
         )
 

filename: tests/test_modeling_common.py
patch: @@ -1775,6 +1775,7 @@ def test_head_pruning(self):
             model = model_class(config=config)
             model.to(torch_device)
             model.eval()
+            model.set_attn_implementation("eager")
             heads_to_prune = {
                 0: list(range(1, self.model_tester.num_attention_heads)),
                 -1: [0],
@@ -1808,6 +1809,7 @@ def test_head_pruning_save_load_from_pretrained(self):
             model = model_class(config=config)
             model.to(torch_device)
             model.eval()
+            model.set_attn_implementation("eager")
             heads_to_prune = {
                 0: list(range(1, self.model_tester.num_attention_heads)),
                 -1: [0],
@@ -1816,7 +1818,7 @@ def test_head_pruning_save_load_from_pretrained(self):
 
             with tempfile.TemporaryDirectory() as temp_dir_name:
                 model.save_pretrained(temp_dir_name)
-                model = model_class.from_pretrained(temp_dir_name)
+                model = model_class.from_pretrained(temp_dir_name, attn_implementation="eager")
                 model.to(torch_device)
 
             with torch.no_grad():
@@ -1852,6 +1854,7 @@ def test_head_pruning_save_load_from_config_init(self):
             model = model_class(config=config)
             model.to(torch_device)
             model.eval()
+            model.set_attn_implementation("eager")
 
             with torch.no_grad():
                 outputs = model(**self._prepare_for_class(inputs_dict, model_class))
@@ -1884,6 +1887,7 @@ def test_head_pruning_integration(self):
             model = model_class(config=config)
             model.to(torch_device)
             model.eval()
+            model.set_attn_implementation("eager")
 
             with torch.no_grad():
                 outputs = model(**self._prepare_for_class(inputs_dict, model_class))
@@ -1894,7 +1898,7 @@ def test_head_pruning_integration(self):
 
             with tempfile.TemporaryDirectory() as temp_dir_name:
                 model.save_pretrained(temp_dir_name)
-                model = model_class.from_pretrained(temp_dir_name)
+                model = model_class.from_pretrained(temp_dir_name, attn_implementation="eager")
                 model.to(torch_device)
 
             with torch.no_grad():