diff --git a/vllm/compilation/collective_fusion.py b/vllm/compilation/collective_fusion.py
index 2717738dd7c2..57bd94c7e8ad 100644
--- a/vllm/compilation/collective_fusion.py
+++ b/vllm/compilation/collective_fusion.py
@@ -1076,11 +1076,15 @@ def __init__(self, config: VllmConfig):
         self.disabled = True
         self.tp_size = get_tensor_model_parallel_world_size()
         if self.tp_size <= 1:
+            logger.warning_once("AllReduce fusion pass is disabled for tp_size <= 1.")
             return
         self.patterns: PatternMatcherPass = PatternMatcherPass(
             pass_name="all_reduce_fusion_pass"
         )
         if config.model_config is None:
+            logger.warning_once(
+                "AllReduce fusion pass is disabled for missing model_config."
+            )
             return
         self.hidden_dim = config.model_config.get_hidden_size()
         self.group = get_tp_group().device_group
@@ -1188,6 +1192,9 @@ def register_patterns(self):
         self.disabled = False
 
     def is_applicable_for_range(self, compile_range: Range) -> bool:
+        if self.disabled:
+            logger.warning_once("AllReduce fusion pass is disabled.")
+            return False
         return compile_range.end <= self.max_token_num
 
     @VllmInductorPass.time_and_log