Add function to remove monkey-patch for text encoder LoRA (#3649)

* merge undoable-monkeypatch

* remove TEXT_ENCODER_TARGET_MODULES, refactoring

* move create_lora_weight_file

Author: takuma104

src/diffusers/loaders.py

@@ -34,7 +34,7 @@
 from .utils import (
     DIFFUSERS_CACHE,
     HF_HUB_OFFLINE,
-    TEXT_ENCODER_TARGET_MODULES,
+    TEXT_ENCODER_ATTN_MODULE,
     _get_model_file,
     deprecate,
     is_safetensors_available,
@@ -955,6 +955,19 @@ def text_encoder_lora_attn_procs(self):
             return self._text_encoder_lora_attn_procs
         return
 
+    def _remove_text_encoder_monkey_patch(self):
+        # Loop over the CLIPAttention module of text_encoder
+        for name, attn_module in self.text_encoder.named_modules():
+            if name.endswith(TEXT_ENCODER_ATTN_MODULE):
+                # Loop over the LoRA layers
+                for _, text_encoder_attr in self._lora_attn_processor_attr_to_text_encoder_attr.items():
+                    # Retrieve the q/k/v/out projection of CLIPAttention
+                    module = attn_module.get_submodule(text_encoder_attr)
+                    if hasattr(module, "old_forward"):
+                        # restore original `forward` to remove monkey-patch
+                        module.forward = module.old_forward
+                        delattr(module, "old_forward")
+
     def _modify_text_encoder(self, attn_processors: Dict[str, LoRAAttnProcessor]):
         r"""
         Monkey-patches the forward passes of attention modules of the text encoder.
@@ -963,37 +976,41 @@ def _modify_text_encoder(self, attn_processors: Dict[str, LoRAAttnProcessor]):
             attn_processors: Dict[str, `LoRAAttnProcessor`]:
                 A dictionary mapping the module names and their corresponding [`~LoRAAttnProcessor`].
         """
-        # Loop over the original attention modules.
-        for name, _ in self.text_encoder.named_modules():
-            if any(x in name for x in TEXT_ENCODER_TARGET_MODULES):
-                # Retrieve the module and its corresponding LoRA processor.
-                module = self.text_encoder.get_submodule(name)
-                # Construct a new function that performs the LoRA merging. We will monkey patch
-                # this forward pass.
-                attn_processor_name = ".".join(name.split(".")[:-1])
-                lora_layer = getattr(attn_processors[attn_processor_name], self._get_lora_layer_attribute(name))
-                old_forward = module.forward
-
-                # create a new scope that locks in the old_forward, lora_layer value for each new_forward function
-                # for more detail, see https://github.com/huggingface/diffusers/pull/3490#issuecomment-1555059060
-                def make_new_forward(old_forward, lora_layer):
-                    def new_forward(x):
-                        return old_forward(x) + lora_layer(x)
-
-                    return new_forward
-
-                # Monkey-patch.
-                module.forward = make_new_forward(old_forward, lora_layer)
-
-    def _get_lora_layer_attribute(self, name: str) -> str:
-        if "q_proj" in name:
-            return "to_q_lora"
-        elif "v_proj" in name:
-            return "to_v_lora"
-        elif "k_proj" in name:
-            return "to_k_lora"
-        else:
-            return "to_out_lora"
+
+        # First, remove any monkey-patch that might have been applied before
+        self._remove_text_encoder_monkey_patch()
+
+        # Loop over the CLIPAttention module of text_encoder
+        for name, attn_module in self.text_encoder.named_modules():
+            if name.endswith(TEXT_ENCODER_ATTN_MODULE):
+                # Loop over the LoRA layers
+                for attn_proc_attr, text_encoder_attr in self._lora_attn_processor_attr_to_text_encoder_attr.items():
+                    # Retrieve the q/k/v/out projection of CLIPAttention and its corresponding LoRA layer.
+                    module = attn_module.get_submodule(text_encoder_attr)
+                    lora_layer = attn_processors[name].get_submodule(attn_proc_attr)
+
+                    # save old_forward to module that can be used to remove monkey-patch
+                    old_forward = module.old_forward = module.forward
+
+                    # create a new scope that locks in the old_forward, lora_layer value for each new_forward function
+                    # for more detail, see https://github.com/huggingface/diffusers/pull/3490#issuecomment-1555059060
+                    def make_new_forward(old_forward, lora_layer):
+                        def new_forward(x):
+                            return old_forward(x) + lora_layer(x)
+
+                        return new_forward
+
+                    # Monkey-patch.
+                    module.forward = make_new_forward(old_forward, lora_layer)
+
+    @property
+    def _lora_attn_processor_attr_to_text_encoder_attr(self):
+        return {
+            "to_q_lora": "q_proj",
+            "to_k_lora": "k_proj",
+            "to_v_lora": "v_proj",
+            "to_out_lora": "out_proj",
+        }
 
     def _load_text_encoder_attn_procs(
         self, pretrained_model_name_or_path_or_dict: Union[str, Dict[str, torch.Tensor]], **kwargs

src/diffusers/utils/__init__.py

@@ -31,7 +31,6 @@
     ONNX_WEIGHTS_NAME,
     SAFETENSORS_WEIGHTS_NAME,
     TEXT_ENCODER_ATTN_MODULE,
-    TEXT_ENCODER_TARGET_MODULES,
     WEIGHTS_NAME,
 )
 from .deprecation_utils import deprecate

src/diffusers/utils/constants.py

@@ -30,5 +30,4 @@
 DIFFUSERS_DYNAMIC_MODULE_NAME = "diffusers_modules"
 HF_MODULES_CACHE = os.getenv("HF_MODULES_CACHE", os.path.join(hf_cache_home, "modules"))
 DEPRECATED_REVISION_ARGS = ["fp16", "non-ema"]
-TEXT_ENCODER_TARGET_MODULES = ["q_proj", "v_proj", "k_proj", "out_proj"]
 TEXT_ENCODER_ATTN_MODULE = ".self_attn"

tests/models/test_lora_layers.py

@@ -163,6 +163,15 @@ def get_dummy_inputs(self):
 
         return noise, input_ids, pipeline_inputs
 
+    def create_lora_weight_file(self, tmpdirname):
+        _, lora_components = self.get_dummy_components()
+        LoraLoaderMixin.save_lora_weights(
+            save_directory=tmpdirname,
+            unet_lora_layers=lora_components["unet_lora_layers"],
+            text_encoder_lora_layers=lora_components["text_encoder_lora_layers"],
+        )
+        self.assertTrue(os.path.isfile(os.path.join(tmpdirname, "pytorch_lora_weights.bin")))
+
     def test_lora_save_load(self):
         pipeline_components, lora_components = self.get_dummy_components()
         sd_pipe = StableDiffusionPipeline(**pipeline_components)
@@ -299,14 +308,45 @@ def test_text_encoder_lora_monkey_patch(self):
             outputs_without_lora, outputs_with_lora
         ), "lora_up_weight are not zero, so the lora outputs should be different to without lora outputs"
 
-    def create_lora_weight_file(self, tmpdirname):
-        _, lora_components = self.get_dummy_components()
-        LoraLoaderMixin.save_lora_weights(
-            save_directory=tmpdirname,
-            unet_lora_layers=lora_components["unet_lora_layers"],
-            text_encoder_lora_layers=lora_components["text_encoder_lora_layers"],
-        )
-        self.assertTrue(os.path.isfile(os.path.join(tmpdirname, "pytorch_lora_weights.bin")))
+    def test_text_encoder_lora_remove_monkey_patch(self):
+        pipeline_components, _ = self.get_dummy_components()
+        pipe = StableDiffusionPipeline(**pipeline_components)
+
+        dummy_tokens = self.get_dummy_tokens()
+
+        # inference without lora
+        outputs_without_lora = pipe.text_encoder(**dummy_tokens)[0]
+        assert outputs_without_lora.shape == (1, 77, 32)
+
+        # create lora_attn_procs with randn up.weights
+        text_attn_procs = create_text_encoder_lora_attn_procs(pipe.text_encoder)
+        set_lora_up_weights(text_attn_procs, randn_weight=True)
+
+        # monkey patch
+        pipe._modify_text_encoder(text_attn_procs)
+
+        # verify that it's okay to release the text_attn_procs which holds the LoRAAttnProcessor.
+        del text_attn_procs
+        gc.collect()
+
+        # inference with lora
+        outputs_with_lora = pipe.text_encoder(**dummy_tokens)[0]
+        assert outputs_with_lora.shape == (1, 77, 32)
+
+        assert not torch.allclose(
+            outputs_without_lora, outputs_with_lora
+        ), "lora outputs should be different to without lora outputs"
+
+        # remove monkey patch
+        pipe._remove_text_encoder_monkey_patch()
+
+        # inference with removed lora
+        outputs_without_lora_removed = pipe.text_encoder(**dummy_tokens)[0]
+        assert outputs_without_lora_removed.shape == (1, 77, 32)
+
+        assert torch.allclose(
+            outputs_without_lora, outputs_without_lora_removed
+        ), "remove lora monkey patch should restore the original outputs"
 
     def test_lora_unet_attn_processors(self):
         with tempfile.TemporaryDirectory() as tmpdirname: