fix pynccl reduce_scatter (#23648)

Co-authored-by: hongchao <hongchao@msh.team>

vllm/distributed/device_communicators/cuda_communicator.py

@@ -152,7 +152,7 @@ class CudaCommunicator(DeviceCommunicatorBase):
                              dtype=input_tensor.dtype,
                              device=input_tensor.device)
 
-        pynccl_comm.reduce_scatter(output, input_)
+        pynccl_comm.reduce_scatter(output, input_tensor)
 
         # Reshape before returning
         return output.movedim(0, dim).contiguous()
@@ -186,9 +186,9 @@ class CudaCommunicator(DeviceCommunicatorBase):
                              device=input_tensor.device)
 
         if sizes is not None:
-            pynccl_comm.reduce_scatterv(output, input_, sizes=sizes)
+            pynccl_comm.reduce_scatterv(output, input_tensor, sizes=sizes)
         else:
-            pynccl_comm.reduce_scatter(output, input_)
+            pynccl_comm.reduce_scatter(output, input_tensor)
 
         # Reshape before returning
         return output.movedim(0, dim).contiguous()