update params to flat params

verl/trainer/fsdp_sft_trainer.py

@@ -277,8 +277,7 @@ def _build_model_optimizer(self):
 
 
         self.optimizer = None
-        # 
-        flat_params = flat_params = [p for p in self.fsdp_model.parameters() if isinstance(p, FlatParameter)]
+        flat_params = [p for p in self.fsdp_model.parameters() if p.requires_grad]
         if self.optim_bwd_hook:
             _apply_optimizer_in_backward(
                 optim.AdamW,