Cannot merge LORA layers when the model is loaded in 8-bit mode

[yangjianxin1]

When I load the model as following, throw the error: Cannot merge LORA layers when the model is loaded in 8-bit mode How can I load model with 4bit when inferencing? model_path = 'decapoda-research/llama-30b-hf' adapter_path = 'timdettmers/guanaco-33b' quantization_config = BitsAndBytesConfig( load_in_4bit=True, bnb_4bit_compute_dtype=torch.bfloat16, bnb_4bit_use_double_quant=True, bnb_4bit_quant_type='nf4' ), model = AutoModelForCausalLM.from_pretrained( model_path, low_cpu_mem_usage=True, load_in_4bit=True, quantization_config=quantization_config, torch_dtype=torch.float16, device_map='auto' ) model = PeftModel.from_pretrained(model, adapter_path) model = model.merge_and_unload()

[yangjianxin1]

model_path = 'decapoda-research/llama-30b-hf' 
adapter_path = 'timdettmers/guanaco-33b'
quantization_config = BitsAndBytesConfig(
    load_in_4bit=True,
    bnb_4bit_compute_dtype=torch.bfloat16,
    bnb_4bit_use_double_quant=True,
    bnb_4bit_quant_type='nf4'
),
model = AutoModelForCausalLM.from_pretrained(
    model_path,
    low_cpu_mem_usage=True,
    load_in_4bit=True,
    quantization_config=quantization_config,
    torch_dtype=torch.float16,
    device_map='auto'
)
model = PeftModel.from_pretrained(model, adapter_path)
model = model.merge_and_unload()

[USBhost]

Just fyi decapoda-research is extremely out of date. Please use huggyllama instead.

[bodaay]

did you solve this? and its the same result with huggyllama

[KKcorps]

@bodaay what is the sie of the adapter.bin you are getting? Mine is like in bytes.

Btw, I just commented out the model = model.merge_and_unload() line and it works. Merging is not necessary

[yangjianxin1]

remove "model = model.merge_and_unload()", and it works.

[bodaay]

@bodaay what is the sie of the adapter.bin you are getting? Mine is like in bytes.

Btw, I just commented out the model = model.merge_and_unload() line and it works. Merging is not necessary

when I re-save the model, its proper 3.2GB

[hemangjoshi37a]

@yangjianxin1, Based on the code snippet you provided, it seems that you are loading the model using AutoModelForCausalLM with 4-bit quantization enabled. However, when attempting to merge the LORA layers using merge_and_unload(), the mentioned error occurs.

To address this issue, we recommend the following approach:

1. Remove the line model = model.merge_and_unload() from your code. The merging step is not necessary for inference and can be omitted.

By removing the merge_and_unload() line, you should be able to successfully load and use the model for inference without encountering the "Cannot merge LORA layers when the model is loaded in 8-bit mode" error.

[larawehbe]

@yangjianxin1, Based on the code snippet you provided, it seems that you are loading the model using AutoModelForCausalLM with 4-bit quantization enabled. However, when attempting to merge the LORA layers using merge_and_unload(), the mentioned error occurs.

To address this issue, we recommend the following approach:

1. Remove the line model = model.merge_and_unload() from your code. The merging step is not necessary for inference and can be omitted.

By removing the merge_and_unload() line, you should be able to successfully load and use the model for inference without encountering the "Cannot merge LORA layers when the model is loaded in 8-bit mode" error.

How can i optain one model so i can use it in llama.cpp if i cant merge them?

Do you have any idea how to make the fine-tuned model applicable inside llama.cpp ?

Any help is highly appreciated

[KiranNadig62]

Removing merge_and_unload() is not the solution!!. Of course, the inference works fine, there is no attempt to merge your LORA weights into the base model. What is the real solution here?

[samos123]

You can see a workaround here: https://github.com/substratusai/model-falcon-7b-instruct/blob/430cf5dfda02c0359122d4ef7f9b6d0c01bb3b39/src/train.ipynb

Effectively I reload the base model in 16 bit to work around the issue. It works fine for my use case.

[ashmitbhattarai]

Anyone found a way to solve this without loading the model in 16bit? My GPU cannot load whole Falcon-40B (in 16-bit), using device_map=auto and offload_folder causes the python code to be Killed. Loading the base model in 4 bit mode and merging with LORA adapters still fail with "Cannot merge LORA layers in 8-bit mode"

[jocastrocUnal]

I hope in the future this code could work... its more natural.

model = peft_model.merge_and_unload()
model.save_pretrained("/model/trained")

[MrigankRaman]

Any updates on this?

[larawehbe]

You can see a workaround here: https://github.com/substratusai/model-falcon-7b-instruct/blob/430cf5dfda02c0359122d4ef7f9b6d0c01bb3b39/src/train.ipynb

Effectively I reload the base model in 16 bit to work around the issue. It works fine for my use case.

The link is broken

[xpang-sf]

You can see a workaround here: https://github.com/substratusai/model-falcon-7b-instruct/blob/430cf5dfda02c0359122d4ef7f9b6d0c01bb3b39/src/train.ipynb

Effectively I reload the base model in 16 bit to work around the issue. It works fine for my use case.

Same here, the link is broken. can pls re-share the link?

[samos123]

New link: https://github.com/substratusai/images/blob/main/model-trainer-huggingface/src/train.ipynb

[xpang-sf]

New link: https://github.com/substratusai/images/blob/main/model-trainer-huggingface/src/train.ipynb

Thank you so much!

[xpang-sf]

New link: https://github.com/substratusai/images/blob/main/model-trainer-huggingface/src/train.ipynb

May I ask another baby question: this is training code and saving model code. After model is saved, did you test to load the saved model and do inference and check whether generated results are good? If so, do you have this separated inference/generating script? Thanks a lot in advance.

[samos123]

Yes in substratus.ai we separate model loading, finetuning and serving in separate images. I did check whether the finetuned model provided different results and it did.

In the notebook that I linked, the following paths are used

# original base model e.g. falcon-7b
model_path = "/content/saved-model/"
# path of final finetuned model (merged model)
trained_model_path = "/content/model"

[xpang-sf]

Yes in substratus.ai we separate model loading, finetuning and serving in separate images. I did check whether the finetuned model provided different results and it did.

In the notebook that I linked, the following paths are used

# original base model e.g. falcon-7b
model_path = "/content/saved-model/"
# path of final finetuned model (merged model)
trained_model_path = "/content/model"

Thank you so much, I will try on my side and let you know.

[Rem1L]

I am worried about whether this quick fix would be harmful to the model's ability? Is there any other way to fix this problem?

[hamidahmadian]

Anyone found a way to solve this without loading the model in 16bit? My GPU cannot load whole Falcon-40B (in 16-bit), using device_map=auto and offload_folder causes the python code to be Killed. Loading the base model in 4 bit mode and merging with LORA adapters still fail with "Cannot merge LORA layers in 8-bit mode"

I found a way that works in my case I hope it works, the problems working with Llama2 in terms of training time, inference time while we just have one (not big memory) GPU can be splited into 3 different parts which I will go through each of them.

• Training: It is not possible to perform pure 8bit or 4bit training so by leveraging parameter efficient fine tuning methods (PEFT) and train for example adapters on top of them we can fine tune Llama2 model. prepare_model_for_kbit_training plays an important role for preparing model for training.
• Merging: on the other hand for merging we can merge our LoRa Layers to Llama2 even on CPU. here is sample template:

llama_model = AutoModel.from_pretrained(model_name, 
                        device_map={"": "cpu"}, 
                        torch_dtype=torch.float16)

model = PeftModel.from_pretrained(llama_model, 
                        peft_model_path, 
                        torch_dtype=torch.float16, 
                        device_map={"": "cpu"})

model = model.merge_and_unload()

model.save_pretrained("merged-model")

• Inference Time: for loading now you can just need to read model from merged-model path, you can load model in 8bit or whatever needs. here is sample template:

model_for_infer = AutoModel.from_pretrained("merged-model",
                        device_map="auto",
                        load_in_8bit=True)

[samuelhkahn]

While not the most elegant solution, @hamidahmadian solution works for me.

[samos123]

I have an issue with this approach when I add a special token. Anyone figure out a way to do that? Code I'm using:

base_model = AutoModelForCausalLM.from_pretrained(
            model_path, torch_dtype=torch.float16, device_map="auto", trust_remote_code=True)
base_model.resize_token_embeddings(len(tokenizer))
model = PeftModel.from_pretrained(base_model, trained_model_path_lora, torch_dtype=torch.float16)
model = model.merge_and_unload()

error observed:

>> model = PeftModel.from_pretrained(base_model, trained_model_path_lora, torch_dtype=torch.float16)
File /usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py:1158, in Module.to.<locals>.convert(t)
   1155 if convert_to_format is not None and t.dim() in (4, 5):
   1156     return t.to(device, dtype if t.is_floating_point() or t.is_complex() else None,
   1157                 non_blocking, memory_format=convert_to_format)
-> 1158 return t.to(device, dtype if t.is_floating_point() or t.is_complex() else None, non_blocking)

NotImplementedError: Cannot copy out of meta tensor; no data!

[eternitybt]

On my laptop with 16GB RAM + 16GB VRAM, @hamidahmadian's solution allows me to load the models, but still gives me an OOM error when doing merge_and_unload(). However, the following works for me:

llama_model = AutoModelForCausalLM.from_pretrained(model_name, device_map={"": "cpu"}, torch_dtype=torch.float16)
model = PeftModel.from_pretrained(llama_model, peft_model_path)
model = model.merge_and_unload()

[praharshbhatt]

This should be the correct way to fix the issue:

peft_model = model

# When you execute the commonly used `model = model.merge_and_unload()`, the error `Cannot merge LORA layers when the model is loaded in 8-bit mode` occurs. The reason is that the base model was loaded as 4 bit. Therefore, the base model must be reloaded as 16 bit.
model = AutoModelForCausalLM.from_pretrained(
    MODEL_NAME,
    torch_dtype=torch.float16,
    load_in_8bit=False,
    device_map="auto",
    trust_remote_code=True,
)
from peft import PeftModel

peft_model = PeftModel.from_pretrained(model, NEW_MODEL_PATH)
merged_model = peft_model.merge_and_unload()