[v1] Support mamba2 (#19327)

Signed-off-by: Chen Zhang <zhangch99@outlook.com>

vllm/engine/arg_utils.py

@@ -1355,12 +1355,17 @@ class EngineArgs:
                                recommend_to_remove=False)
             return False
 
-        # No Mamba or Encoder-Decoder so far.
+        # No Encoder-Decoder, not all Mamba so far.
         if not model_config.is_v1_compatible:
             _raise_or_fallback(feature_name=model_config.architectures,
                                recommend_to_remove=False)
             return False
 
+        # V1 mamba models are unoptimized.
+        if model_config.has_inner_state and _warn_or_fallback(
+                feature_name="Mamba"):
+            return False
+
         # No Concurrent Partial Prefills so far.
         if (self.max_num_partial_prefills
                 != SchedulerConfig.max_num_partial_prefills