Fix RMSNorm API CALL mismatch issue. (#10032)

Co-authored-by: Hubert Lu <Hubert.Lu@amd.com>

python/sglang/srt/layers/layernorm.py

@@ -18,6 +18,7 @@ from typing import Optional, Tuple, Union
 
 import torch
 import torch.nn as nn
+from packaging.version import Version
 
 from sglang.srt.custom_op import CustomOp
 from sglang.srt.utils import (
@@ -49,8 +50,11 @@ if _use_aiter:
     from aiter import rmsnorm2d_fwd as rms_norm
     from aiter import rmsnorm2d_fwd_with_add as fused_add_rms_norm
 elif _is_hip:
+    import vllm
     from vllm._custom_ops import fused_add_rms_norm, rms_norm
 
+    _vllm_version = Version(vllm.__version__)
+
 logger = logging.getLogger(__name__)
 
 if _is_npu:
@@ -127,8 +131,21 @@ class RMSNorm(CustomOp):
             # NOTE: Remove this if aiter kernel supports discontinuous input
             x = x.contiguous()
         if residual is not None:
-            fused_add_rms_norm(x, residual, self.weight.data, self.variance_epsilon)
+            if _vllm_version < Version("0.9"):
-            return x, residual
+                fused_add_rms_norm(x, residual, self.weight.data, self.variance_epsilon)
+                return x, residual
+            else:
+                residual_out = torch.empty_like(x)
+                output = torch.empty_like(x)
+                fused_add_rms_norm(
+                    output,
+                    x,
+                    residual_out,
+                    residual,
+                    self.weight.data,
+                    self.variance_epsilon,
+                )
+                return output, residual_out
         out = torch.empty_like(x)
         rms_norm(out, x, self.weight.data, self.variance_epsilon)
         return out