[BugFix] Restore vllm_c IR op priority and torch.nn.RMSNorm for Qwen-Image (Same As #5009) (#5017)

Signed-off-by: NumberWan <wantszkin2003@gmail.com>

tests/platforms/test_cuda_ir_op_priority.py

@@ -0,0 +1,38 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import pytest
+from vllm.config import CompilationConfig, CompilationMode, DeviceConfig, VllmConfig
+
+from vllm_omni.platforms.cuda.platform import CudaOmniPlatform
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+def _vllm_config(*, backend: str = "inductor", mode: CompilationMode) -> VllmConfig:
+    return VllmConfig(
+        device_config=DeviceConfig(device="cpu"),
+        compilation_config=CompilationConfig(backend=backend, mode=mode),
+    )
+
+
+@pytest.mark.parametrize(
+    "mode",
+    [CompilationMode.NONE, CompilationMode.VLLM_COMPILE, CompilationMode.STOCK_TORCH_COMPILE],
+)
+def test_cuda_default_ir_op_priority_prefers_vllm_c_when_inductor_backend(mode: CompilationMode) -> None:
+    """Regression for #4964: inductor-active configs must not switch to native-only."""
+    priority = CudaOmniPlatform.get_default_ir_op_priority(_vllm_config(mode=mode))
+    assert priority.rms_norm == ["vllm_c", "native"]
+    assert priority.fused_add_rms_norm == ["vllm_c", "native"]
+
+
+def test_cuda_default_ir_op_priority_with_oink(monkeypatch: pytest.MonkeyPatch) -> None:
+    import vllm.envs as envs
+
+    monkeypatch.setattr(envs, "VLLM_USE_OINK_OPS", True)
+    priority = CudaOmniPlatform.get_default_ir_op_priority(
+        _vllm_config(mode=CompilationMode.VLLM_COMPILE),
+    )
+    assert priority.rms_norm == ["oink", "vllm_c", "native"]
+    assert priority.fused_add_rms_norm == ["oink", "vllm_c", "native"]

vllm_omni/diffusion/models/qwen_image/qwen_image_transformer.py

@@ -17,7 +17,6 @@ from diffusers.models.embeddings import TimestepEmbedding, Timesteps
 from diffusers.models.modeling_outputs import Transformer2DModelOutput
 from diffusers.models.normalization import AdaLayerNormContinuous
 from vllm.logger import init_logger
-from vllm.model_executor.layers.layernorm import RMSNorm
 from vllm.model_executor.layers.linear import (
     ColumnParallelLinear,
     QKVParallelLinear,
@@ -555,8 +554,8 @@ class QwenImageCrossAttention(nn.Module):
         self.query_num_heads = self.to_qkv.num_heads
         self.kv_num_heads = self.to_qkv.num_kv_heads
 
-        self.norm_q = RMSNorm(head_dim, eps=eps) if qk_norm else nn.Identity()
-        self.norm_k = RMSNorm(head_dim, eps=eps) if qk_norm else nn.Identity()
+        self.norm_q = nn.RMSNorm(head_dim, eps=eps) if qk_norm else nn.Identity()
+        self.norm_k = nn.RMSNorm(head_dim, eps=eps) if qk_norm else nn.Identity()
 
         self.inner_dim = out_dim if out_dim is not None else head_dim * self.total_num_heads
 
@@ -593,8 +592,8 @@ class QwenImageCrossAttention(nn.Module):
             prefix=f"{prefix}.to_out.0",
         )
 
-        self.norm_added_q = RMSNorm(head_dim, eps=eps)
-        self.norm_added_k = RMSNorm(head_dim, eps=eps)
+        self.norm_added_q = nn.RMSNorm(head_dim, eps=eps)
+        self.norm_added_k = nn.RMSNorm(head_dim, eps=eps)
 
         self.attn = Attention(
             num_heads=self.query_num_heads,
@@ -1007,7 +1006,7 @@ class QwenImageTransformer2DModel(CachedTransformer):
             quant_config=quant_config,
         )
 
-        self.txt_norm = RMSNorm(joint_attention_dim, eps=1e-6)
+        self.txt_norm = nn.RMSNorm(joint_attention_dim, eps=1e-6)
 
         # Entry projections (image/text) are kept full precision —
         # small sensitive layers at the network boundary (see #2728).

vllm_omni/platforms/cuda/platform.py

@@ -224,16 +224,8 @@ class CudaOmniPlatform(OmniPlatform, CudaPlatformBase):
 
     @classmethod
     def get_default_ir_op_priority(cls, vllm_config: VllmConfig) -> IrOpPriorityConfig:
-        """Copied from upstream CudaPlatformBase with inductor-aware logic.
-
-        When inductor is active (compiling) use native as the default;
-        otherwise prefer vllm_c kernels where available.
-        """
-        from vllm.config.compilation import CompilationMode
-
-        cc = vllm_config.compilation_config
-        using_inductor = cc.backend == "inductor" and cc.mode != CompilationMode.NONE
-        default = ["native"] if using_inductor else ["vllm_c", "native"]
+        """Prefer ``vllm_c`` CUDA kernels over ``native`` for diffusion IR ops."""
+        default = ["vllm_c", "native"]
 
         # Use oink if enabled for rms_norm
         # TODO(Laurawly/luka): remove this env var,