OPTForCausalLM lm_head input size should be config.word_embed_proj_dim (#17225)

src/transformers/models/opt/modeling_opt.py

@@ -786,7 +786,7 @@ class OPTForCausalLM(OPTPreTrainedModel):
         self.model = OPTModel(config)
 
         # the lm_head weight is automatically tied to the embed tokens weight
-        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
+        self.lm_head = nn.Linear(config.word_embed_proj_dim, config.vocab_size, bias=False)
 
         # Initialize weights and apply final processing
         self.post_init()