[MM][Bugfix] Replace PatchEmbed's conv3d to linear layer (#27418)

Signed-off-by: Isotr0py <mozf@mail2.sysu.edu.cn>
Co-authored-by: Roger Wang <hey@rogerw.io>

vllm/model_executor/models/glm4_1v.py

@@ -60,6 +60,7 @@ from vllm.model_executor.layers.linear import (
     ColumnParallelLinear,
     MergedColumnParallelLinear,
     QKVParallelLinear,
+    ReplicatedLinear,
     RowParallelLinear,
 )
 from vllm.model_executor.layers.quantization import QuantizationConfig
@@ -98,7 +99,11 @@ from .utils import (
     init_vllm_registered_model,
     maybe_prefix,
 )
-from .vision import get_vit_attn_backend, run_dp_sharded_mrope_vision_model
+from .vision import (
+    conv3d_to_linear_weight,
+    get_vit_attn_backend,
+    run_dp_sharded_mrope_vision_model,
+)
 
 logger = init_logger(__name__)
 
@@ -478,18 +483,15 @@ class Glm4vVisionPatchEmbed(nn.Module):
         self.hidden_size = hidden_size
 
         kernel_size = (temporal_patch_size, patch_size, patch_size)
-        self.proj = nn.Conv3d(
+        self.proj = ReplicatedLinear(
-            in_channels,
+            in_channels * math.prod(kernel_size),
             hidden_size,
-            kernel_size=kernel_size,
-            stride=kernel_size,
             bias=True,
+            return_bias=False,
         )
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
-        L, C = x.shape
+        x = self.proj(x)
-        x = x.view(L, -1, self.temporal_patch_size, self.patch_size, self.patch_size)
-        x = self.proj(x).view(L, self.hidden_size)
         return x
 
 
@@ -887,6 +889,9 @@ class Glm4vVisionTransformer(nn.Module):
         loaded_params: set[str] = set()
 
         for name, loaded_weight in weights:
+            if name.endswith("patch_embed.proj.weight"):
+                loaded_weight = conv3d_to_linear_weight(loaded_weight)
+
             for param_name, weight_name, shard_id in stacked_params_mapping:
                 if weight_name not in name:
                     continue

vllm/model_executor/models/qwen2_5_vl.py

@@ -26,6 +26,7 @@
 # limitations under the License.
 """Inference-only Qwen2.5-VL model compatible with HuggingFace weights."""
 
+import math
 from collections.abc import Callable, Iterable, Mapping, Sequence
 from functools import lru_cache, partial
 from typing import Annotated, Any, Literal, TypeAlias
@@ -56,6 +57,7 @@ from vllm.model_executor.layers.linear import (
     ColumnParallelLinear,
     MergedColumnParallelLinear,
     QKVParallelLinear,
+    ReplicatedLinear,
     RowParallelLinear,
 )
 from vllm.model_executor.layers.quantization import QuantizationConfig
@@ -98,7 +100,11 @@ from .utils import (
     init_vllm_registered_model,
     maybe_prefix,
 )
-from .vision import get_vit_attn_backend, run_dp_sharded_mrope_vision_model
+from .vision import (
+    conv3d_to_linear_weight,
+    get_vit_attn_backend,
+    run_dp_sharded_mrope_vision_model,
+)
 
 logger = init_logger(__name__)
 
@@ -532,18 +538,15 @@ class Qwen2_5_VisionPatchEmbed(nn.Module):
         self.hidden_size = hidden_size
 
         kernel_size = (temporal_patch_size, patch_size, patch_size)
-        self.proj = nn.Conv3d(
+        self.proj = ReplicatedLinear(
-            in_channels,
+            in_channels * math.prod(kernel_size),
             hidden_size,
-            kernel_size=kernel_size,
-            stride=kernel_size,
             bias=False,
+            return_bias=False,
         )
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
-        L, C = x.shape
+        x = self.proj(x)
-        x = x.view(L, -1, self.temporal_patch_size, self.patch_size, self.patch_size)
-        x = self.proj(x).view(L, self.hidden_size)
         return x
 
 
@@ -950,6 +953,9 @@ class Qwen2_5_VisionTransformer(nn.Module):
         loaded_params: set[str] = set()
 
         for name, loaded_weight in weights:
+            if name.endswith("patch_embed.proj.weight"):
+                loaded_weight = conv3d_to_linear_weight(loaded_weight)
+
             for param_name, weight_name, shard_id in stacked_params_mapping:
                 if weight_name not in name:
                     continue

vllm/model_executor/models/qwen2_vl.py

@@ -25,6 +25,7 @@
 # limitations under the License.
 """Inference-only Qwen2-VL model compatible with HuggingFace weights."""
 
+import math
 from collections.abc import Callable, Iterable, Mapping, Sequence
 from functools import partial
 from typing import Annotated, Any, Literal, TypeAlias
@@ -53,7 +54,11 @@ from vllm.distributed import parallel_state, tensor_model_parallel_all_gather
 from vllm.distributed import utils as dist_utils
 from vllm.logger import init_logger
 from vllm.model_executor.layers.activation import QuickGELU
-from vllm.model_executor.layers.linear import ColumnParallelLinear, RowParallelLinear
+from vllm.model_executor.layers.linear import (
+    ColumnParallelLinear,
+    ReplicatedLinear,
+    RowParallelLinear,
+)
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.layers.rotary_embedding.common import (
     dispatch_rotary_emb_function,
@@ -100,7 +105,11 @@ from .utils import (
     init_vllm_registered_model,
     maybe_prefix,
 )
-from .vision import get_vit_attn_backend, run_dp_sharded_mrope_vision_model
+from .vision import (
+    conv3d_to_linear_weight,
+    get_vit_attn_backend,
+    run_dp_sharded_mrope_vision_model,
+)
 
 logger = init_logger(__name__)
 
@@ -561,18 +570,15 @@ class Qwen2VisionPatchEmbed(nn.Module):
         self.embed_dim = embed_dim
 
         kernel_size = (temporal_patch_size, patch_size, patch_size)
-        self.proj = nn.Conv3d(
+        self.proj = ReplicatedLinear(
-            in_channels,
+            in_channels * math.prod(kernel_size),
             embed_dim,
-            kernel_size=kernel_size,
-            stride=kernel_size,
             bias=False,
+            return_bias=False,
         )
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
-        L, C = x.shape
+        x = self.proj(x)
-        x = x.view(L, -1, self.temporal_patch_size, self.patch_size, self.patch_size)
-        x = self.proj(x).view(L, self.embed_dim)
         return x
 
 
@@ -835,6 +841,9 @@ class Qwen2VisionTransformer(nn.Module):
         loaded_params: set[str] = set()
 
         for name, loaded_weight in weights:
+            if name.endswith("patch_embed.proj.weight"):
+                loaded_weight = conv3d_to_linear_weight(loaded_weight)
+
             for param_name, weight_name, shard_id in stacked_params_mapping:
                 if weight_name not in name:
                     continue

vllm/model_executor/models/qwen3_omni_moe_thinker.py

@@ -22,6 +22,7 @@
 # limitations under the License.
 """Inference-only Qwen3-Omni-Moe model (thinker part)."""
 
+import math
 from collections.abc import Callable, Iterable, Mapping, Sequence
 from functools import partial
 from typing import Any
@@ -53,7 +54,11 @@ from vllm.config import VllmConfig
 from vllm.distributed import get_pp_group
 from vllm.logger import init_logger
 from vllm.model_executor.layers.activation import _ACTIVATION_REGISTRY
-from vllm.model_executor.layers.linear import ColumnParallelLinear, RowParallelLinear
+from vllm.model_executor.layers.linear import (
+    ColumnParallelLinear,
+    ReplicatedLinear,
+    RowParallelLinear,
+)
 from vllm.model_executor.layers.logits_processor import LogitsProcessor
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.layers.vocab_parallel_embedding import ParallelLMHead
@@ -98,7 +103,11 @@ from .utils import (
     _merge_multimodal_embeddings,
     maybe_prefix,
 )
-from .vision import get_llm_pos_ids_for_vision, get_vit_attn_backend
+from .vision import (
+    conv3d_to_linear_weight,
+    get_llm_pos_ids_for_vision,
+    get_vit_attn_backend,
+)
 
 try:
     import flash_attn
@@ -131,18 +140,16 @@ class Qwen3_VisionPatchEmbed(nn.Module):
         self.hidden_size = hidden_size
 
         kernel_size = (temporal_patch_size, patch_size, patch_size)
-        self.proj = nn.Conv3d(
+        self.proj = ReplicatedLinear(
-            in_channels,
+            in_channels * math.prod(kernel_size),
             hidden_size,
-            kernel_size=kernel_size,
-            stride=kernel_size,
             bias=True,
+            return_bias=False,
         )
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
         L, C = x.shape
-        x = x.view(L, -1, self.temporal_patch_size, self.patch_size, self.patch_size)
+        x = self.proj(x)
-        x = self.proj(x).view(L, self.hidden_size)
         return x
 
 
@@ -559,6 +566,9 @@ class Qwen3Omni_VisionTransformer(nn.Module):
         loaded_params: set[str] = set()
 
         for name, loaded_weight in weights:
+            if name.endswith("patch_embed.proj.weight"):
+                loaded_weight = conv3d_to_linear_weight(loaded_weight)
+
             for param_name, weight_name, shard_id in stacked_params_mapping:
                 if weight_name not in name:
                     continue

vllm/model_executor/models/qwen3_vl.py

@@ -24,6 +24,7 @@
 # limitations under the License.
 """Inference-only Qwen3VL model compatible with HuggingFace weights."""
 
+import math
 from collections.abc import Callable, Iterable, Mapping, Sequence
 from functools import partial
 from itertools import islice
@@ -56,7 +57,11 @@ from vllm.config.multimodal import BaseDummyOptions, VideoDummyOptions
 from vllm.distributed import get_pp_group
 from vllm.logger import init_logger
 from vllm.model_executor.layers.activation import _ACTIVATION_REGISTRY
-from vllm.model_executor.layers.linear import ColumnParallelLinear, RowParallelLinear
+from vllm.model_executor.layers.linear import (
+    ColumnParallelLinear,
+    ReplicatedLinear,
+    RowParallelLinear,
+)
 from vllm.model_executor.layers.logits_processor import LogitsProcessor
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.layers.vocab_parallel_embedding import ParallelLMHead
@@ -107,7 +112,11 @@ from .utils import (
     _merge_multimodal_embeddings,
     maybe_prefix,
 )
-from .vision import get_vit_attn_backend, run_dp_sharded_mrope_vision_model
+from .vision import (
+    conv3d_to_linear_weight,
+    get_vit_attn_backend,
+    run_dp_sharded_mrope_vision_model,
+)
 
 logger = init_logger(__name__)
 
@@ -129,18 +138,15 @@ class Qwen3_VisionPatchEmbed(nn.Module):
         self.hidden_size = hidden_size
 
         kernel_size = (temporal_patch_size, patch_size, patch_size)
-        self.proj = nn.Conv3d(
+        self.proj = ReplicatedLinear(
-            in_channels,
+            in_channels * math.prod(kernel_size),
             hidden_size,
-            kernel_size=kernel_size,
-            stride=kernel_size,
             bias=True,
+            return_bias=False,
         )
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
-        L, C = x.shape
+        x = self.proj(x)
-        x = x.view(L, -1, self.temporal_patch_size, self.patch_size, self.patch_size)
-        x = self.proj(x).view(L, self.hidden_size)
         return x
 
 
@@ -576,6 +582,9 @@ class Qwen3_VisionTransformer(nn.Module):
         loaded_params: set[str] = set()
 
         for name, loaded_weight in weights:
+            if name.endswith("patch_embed.proj.weight"):
+                loaded_weight = conv3d_to_linear_weight(loaded_weight)
+
             for param_name, weight_name, shard_id in stacked_params_mapping:
                 if weight_name not in name:
                     continue

vllm/model_executor/models/vision.py

@@ -544,3 +544,19 @@ def get_llm_pos_ids_for_vision(
     llm_pos_ids_list.append(_llm_pos_ids + start_idx)
     llm_pos_ids = torch.cat(llm_pos_ids_list, dim=1)
     return llm_pos_ids
+
+
+# Due to a performance regression with Conv3D in PyTorch2.9, we reshape
+# Conv3D weights to Linear weights for better performance.
+# See: https://github.com/vllm-project/vllm/issues/27406
+# and https://github.com/pytorch/pytorch/issues/166122
+# FIXME(Isotr0py): Revert the PR introduces this workaround
+# (https://github.com/vllm-project/vllm/pull/27418),
+# once the performance issue is resolved in PyTorch.
+def conv3d_to_linear_weight(conv3d_weight: torch.Tensor) -> torch.Tensor:
+    """
+    Reshape Conv3D weight to Linear weight. Only work when kernel_size==stride.
+    """
+    out_channels, in_channels, kt, kh, kw = conv3d_weight.shape
+    linear_weight = conv3d_weight.reshape(out_channels, in_channels * kt * kh * kw)
+    return linear_weight