[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/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(
-            in_channels,
+        self.proj = ReplicatedLinear(
+            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).view(L, self.hidden_size)
+        x = self.proj(x)
         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