log a warning when there are missing keys in the LoRA loading.

Author: sayakpaul

src/diffusers/loaders/lora_pipeline.py

@@ -1367,6 +1367,14 @@ def load_lora_into_transformer(
                         f" {unexpected_keys}. "
                     )
 
+                # Filter missing keys specific to the current adapter.
+                missing_keys = getattr(incompatible_keys, "missing_keys", None)
+                if missing_keys:
+                    logger.warning(
+                        f"Loading adapter weights from state_dict led to missing keys in the model: "
+                        f" {missing_keys}. "
+                    )
+
             # Offload back.
             if is_model_cpu_offload:
                 _pipeline.enable_model_cpu_offload()
@@ -1933,14 +1941,22 @@ def load_lora_into_transformer(
             incompatible_keys = set_peft_model_state_dict(transformer, state_dict, adapter_name, **peft_kwargs)
 
             if incompatible_keys is not None:
-                # check only for unexpected keys
+                # Check only for unexpected keys.
                 unexpected_keys = getattr(incompatible_keys, "unexpected_keys", None)
                 if unexpected_keys:
                     logger.warning(
                         f"Loading adapter weights from state_dict led to unexpected keys not found in the model: "
                         f" {unexpected_keys}. "
                     )
 
+                # Filter missing keys specific to the current adapter.
+                missing_keys = getattr(incompatible_keys, "missing_keys", None)
+                if missing_keys:
+                    logger.warning(
+                        f"Loading adapter weights from state_dict led to missing keys in the model: "
+                        f" {missing_keys}. "
+                    )
+
             # Offload back.
             if is_model_cpu_offload:
                 _pipeline.enable_model_cpu_offload()
@@ -2288,6 +2304,14 @@ def load_lora_into_transformer(cls, state_dict, network_alphas, transformer, ada
                         f" {unexpected_keys}. "
                     )
 
+                # Filter missing keys specific to the current adapter.
+                missing_keys = getattr(incompatible_keys, "missing_keys", None)
+                if missing_keys:
+                    logger.warning(
+                        f"Loading adapter weights from state_dict led to missing keys in the model: "
+                        f" {missing_keys}. "
+                    )
+
             # Offload back.
             if is_model_cpu_offload:
                 _pipeline.enable_model_cpu_offload()
@@ -2726,6 +2750,14 @@ def load_lora_into_transformer(
                         f" {unexpected_keys}. "
                     )
 
+                # Filter missing keys specific to the current adapter.
+                missing_keys = getattr(incompatible_keys, "missing_keys", None)
+                if missing_keys:
+                    logger.warning(
+                        f"Loading adapter weights from state_dict led to missing keys in the model: "
+                        f" {missing_keys}. "
+                    )
+
             # Offload back.
             if is_model_cpu_offload:
                 _pipeline.enable_model_cpu_offload()

src/diffusers/loaders/unet.py

@@ -363,6 +363,14 @@ def _process_lora(
                         f" {unexpected_keys}. "
                     )
 
+                # Filter missing keys specific to the current adapter.
+                missing_keys = getattr(incompatible_keys, "missing_keys", None)
+                if missing_keys:
+                    logger.warning(
+                        f"Loading adapter weights from state_dict led to missing keys in the model: "
+                        f" {missing_keys}. "
+                    )
+
         return is_model_cpu_offload, is_sequential_cpu_offload
 
     @classmethod