RuntimeError: only Tensors of floating point dtype can require gradients for QLoRA since transformers 4.40

[dipanjanS]

System Info

transformers-4.40.1
peft-0.10.0
accelerate-0.30.0 
bitsandbytes-0.43.1 
evaluate-0.4.2 

Who can help?

@pacman100

Information

• The official example scripts
• My own modified scripts

Tasks

• An officially supported task in the examples folder
• My own task or dataset (give details below)

Reproduction

This is the colab notebook for a simple fine-tuning of a DistilBERT model using QLoRA

The main code snippet of interest which is erroring out:

model_checkpoint = "distilbert/distilbert-base-uncased"

id2label = {0: "NEGATIVE", 1: "POSITIVE"}
label2id = {"NEGATIVE": 0, "POSITIVE": 1}

import torch
from transformers import AutoModelForSequenceClassification, TrainingArguments, Trainer, BitsAndBytesConfig

config = BitsAndBytesConfig(
    load_in_4bit=True, # quantize the model to 4-bits when you load it
    bnb_4bit_quant_type="nf4", # use a special 4-bit data type for weights initialized from a normal distribution
    bnb_4bit_use_double_quant=True, # nested quantization scheme to quantize the already quantized weights
    bnb_4bit_compute_dtype=torch.bfloat16, # use bfloat16 for faster computation,
)

model = AutoModelForSequenceClassification.from_pretrained(model_checkpoint,
                                                           id2label=id2label,
                                                           label2id=label2id,
                                                           num_labels=2,
                                                           quantization_config=config)

from peft import prepare_model_for_kbit_training

model = prepare_model_for_kbit_training(model)

from peft import LoraConfig, get_peft_model, TaskType, replace_lora_weights_loftq

config = LoraConfig(
    r=8,
    lora_alpha=32,
    target_modules=["q_lin", "k_lin", "v_lin", "out_lin"],
    lora_dropout=0.05,
    bias="none",
    task_type=TaskType.SEQ_CLS)

peft_model = get_peft_model(model, config)
replace_lora_weights_loftq(peft_model)
print_trainable_parameters(peft_model)

Error happens in the line peft_model = get_peft_model(model, config) above when the PEFT model is being made. Error trace is as follows.

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
[<ipython-input-41-79fb3abcb23e>](https://localhost:8080/#) in <cell line: 19>()
     17     model.get_input_embeddings().register_forward_hook(make_inputs_require_grad)
     18 
---> 19 peft_model = get_peft_model(model, config)
     20 replace_lora_weights_loftq(peft_model)
     21 print_trainable_parameters(peft_model)

5 frames
[/usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py](https://localhost:8080/#) in requires_grad_(self, requires_grad)
   2433         """
   2434         for p in self.parameters():
-> 2435             p.requires_grad_(requires_grad)
   2436         return self
   2437 

RuntimeError: only Tensors of floating point dtype can require gradients

Expected behavior

Ideally the model should get created and then fine-tuned. The same notebook used to work fine with transformers==4.38 but something might have changed as it is no longer working with transformers==4.40, have validated the same that when I downgrade this code still works. I want some help in figuring out if something is wrong in the code which I need to change \ fundamentally doing wrong or there is a deeper issue.

[BenjaminBossan]

Yes, I can reproduce the error. The reason is that since transformers==4.40, the pre_classifier module of this model is converted to a bitsandbytes Linear4bit when instead of being a normal PyTorch nn.Linear. As this module as being added to the modules_to_save, PEFT tries to enable gradients on it, resulting in the error you see. We'll discuss this internally and think of an appropriate fix. In the meantime, if possible, downgrade to an earlier transformers version.

[dipanjanS]

Thanks for checking on this, appreciate it. Sure for now I'll use the earlier version for my projects and demos.!

…

On Fri, May 10, 2024, 3:10 PM Benjamin Bossan ***@***.***> wrote: Yes, I can reproduce the error. The reason is that since transformers==4.40, the pre_classifier module of this model is converted to a bitsandbytes Linear4bit when instead of being a normal PyTorch nn.Linear. As this module as being added to the modules_to_save, PEFT tries to enable gradients on it, resulting in the error you see. We'll discuss this internally and think of an appropriate fix. In the meantime, if possible, downgrade to an earlier transformers version. — Reply to this email directly, view it on GitHub <#1720 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA2J3R72Z5SFTDPMDVSE37DZBSIXHAVCNFSM6AAAAABHO6UKESVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDCMBUGI4TAMRTGE> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[younesbelkada]

Hi @dipanjanS !
Thanks for the issue, I had a deeper look. Previously there was a silent bug in transformers that was quantizing the pre_classifier layer, which shouldn't happen as only the last layer should be quantized.

huggingface/transformers#29958 introduced a fix for that and introduced this bug you are sharing which shouldn't be really a bug since the pre_classifier should be quantized at first place, only the last layer shouldn't be quantized.

To temporary fix your issue, can you load the 4-bit model with: llm_int8_skip_modules=["classifier", "pre_classifier"] ?

model_checkpoint = "distilbert/distilbert-base-uncased"

id2label = {0: "NEGATIVE", 1: "POSITIVE"}
label2id = {"NEGATIVE": 0, "POSITIVE": 1}

import torch
from transformers import AutoModelForSequenceClassification, TrainingArguments, Trainer, BitsAndBytesConfig

config = BitsAndBytesConfig(
    load_in_4bit=True, # quantize the model to 4-bits when you load it
    bnb_4bit_quant_type="nf4", # use a special 4-bit data type for weights initialized from a normal distribution
    bnb_4bit_use_double_quant=True, # nested quantization scheme to quantize the already quantized weights
    bnb_4bit_compute_dtype=torch.bfloat16, # use bfloat16 for faster computation,
+     llm_int8_skip_modules=["classifier", "pre_classifier"]
)

model = AutoModelForSequenceClassification.from_pretrained(model_checkpoint,
                                                           id2label=id2label,
                                                           label2id=label2id,
                                                           num_labels=2,
                                                           quantization_config=config)

from peft import prepare_model_for_kbit_training

model = prepare_model_for_kbit_training(model)

from peft import LoraConfig, get_peft_model, TaskType, replace_lora_weights_loftq

config = LoraConfig(
    r=8,
    lora_alpha=32,
    target_modules=["q_lin", "k_lin", "v_lin", "out_lin"],
    lora_dropout=0.05,
    bias="none",
    task_type=TaskType.SEQ_CLS)

peft_model = get_peft_model(model, config)
replace_lora_weights_loftq(peft_model)
print_trainable_parameters(peft_model)

[dipanjanS]

Awesome, can confirm this definitely works! Just wanted to check going forward should I explicitly mention those classifier layers to be skipped in the BnB configuration? or would this be automatically handled in a future release. Based on your recommendation I will try to use that going forward

…

On Mon, May 13, 2024 at 8:29 PM Younes Belkada ***@***.***> wrote: Hi @dipanjanS <https://github.com/dipanjanS> ! Thanks for the issue, I had a deeper look. Previously there was a silent bug in transformers that was quantizing the pre_classifier layer, which shouldn't happen as only the last layer should be quantized. huggingface/transformers#29958 <huggingface/transformers#29958> introduced a fix for that and introduced this bug you are sharing which shouldn't be really a bug since the pre_classifier should be quantized at first place, only the last layer shouldn't be quantized. To temporary fix your issue, can you load the 4-bit model with: llm_int8_skip_modules=["classifier", "pre_classifier"] ? model_checkpoint = "distilbert/distilbert-base-uncased" id2label = {0: "NEGATIVE", 1: "POSITIVE"} label2id = {"NEGATIVE": 0, "POSITIVE": 1} import torch from transformers import AutoModelForSequenceClassification, TrainingArguments, Trainer, BitsAndBytesConfig config = BitsAndBytesConfig( load_in_4bit=True, # quantize the model to 4-bits when you load it bnb_4bit_quant_type="nf4", # use a special 4-bit data type for weights initialized from a normal distribution bnb_4bit_use_double_quant=True, # nested quantization scheme to quantize the already quantized weights bnb_4bit_compute_dtype=torch.bfloat16, # use bfloat16 for faster computation,+ llm_int8_skip_modules=["classifier", "pre_classifier"] ) model = AutoModelForSequenceClassification.from_pretrained(model_checkpoint, id2label=id2label, label2id=label2id, num_labels=2, quantization_config=config) from peft import prepare_model_for_kbit_training model = prepare_model_for_kbit_training(model) from peft import LoraConfig, get_peft_model, TaskType, replace_lora_weights_loftq config = LoraConfig( r=8, lora_alpha=32, target_modules=["q_lin", "k_lin", "v_lin", "out_lin"], lora_dropout=0.05, bias="none", task_type=TaskType.SEQ_CLS) peft_model = get_peft_model(model, config) replace_lora_weights_loftq(peft_model) print_trainable_parameters(peft_model) — Reply to this email directly, view it on GitHub <#1720 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA2J3R77JKB4MFDC2TFJ4X3ZCDIL5AVCNFSM6AAAAABHO6UKESVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDCMBXHA3TQNZZGM> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[younesbelkada]

Hi @dipanjanS
Thanks ! Yes, since there was a bug on previous transformers version, we will not automatically handle this in a future transformers release