[Bugfix] Weight loading fix for OPT model (vllm-project#9042)

Co-authored-by: dvres <[email protected]>
Signed-off-by: Sumit Dubey <[email protected]>

vllm/model_executor/models/opt.py

@@ -353,7 +353,7 @@ def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]]):
         ]
         params_dict = dict(self.named_parameters(remove_duplicate=False))
         for name, loaded_weight in weights:
-            if "lm_head.weight" in name:
+            if "lm_head.weight" in name and self.config.tie_word_embeddings:
                 continue
             if name.startswith("decoder."):
                 name = "model." + name