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[Bug] Im getting 'grad_norm': nan, 'learning_rate': 0.0 during GRPO #2824

@catalinursu01

Description

@catalinursu01

I use the last version of vllm and unsloth,and a custom LLaMA 3.3 70B fine-tuned using unsloth. I attached my grpo config, and trainer, I tried changing parameters and setting a custom optimiser but it seems like unsloth rewrites it anyway. Is there anyone who could tell me what could be the issue here?

model, tokenizer = FastLanguageModel.from_pretrained(
    model_name=args.model_repo,
    max_seq_length=args.max_seq_length,
    load_in_4bit=True,
    dtype=None,
    fast_inference = True,
    max_lora_rank = 64,  
)


model.gradient_checkpointing_enable()

tokenizer.pad_token = tokenizer.eos_token

robotics_data = load_robotics_dataset(args.data_path)
grpo_dataset = prepare_grpo_dataset(robotics_data, tokenizer)

from vllm import SamplingParams
vllm_sampling_params = SamplingParams(
    min_p = 0.1,
    top_p = 1.0,
    top_k = -1,
    seed = 3407,
    stop = [tokenizer.eos_token],
    include_stop_str_in_output = True,
)

training_args = GRPOConfig(
    vllm_sampling_params = vllm_sampling_params,
    temperature = 1.0,
    learning_rate=5e-7,  # Conservative for 70B
    weight_decay=0.01,
    warmup_steps=20,
    lr_scheduler_type="linear",
    optim="adamw_8bit",  
    logging_steps=1,
    per_device_train_batch_size=1,
    gradient_accumulation_steps=4,
    num_generations=2,
    max_prompt_length = 512,
    max_completion_length = 1024, 
    max_steps=args.max_steps,
    save_steps=100,
    report_to="none",
    output_dir="grpo_outputs",
    eval_strategy = "steps",
    eval_steps = 1,
    fp16_full_eval = True,
    eval_accumulation_steps = 1,
)

grpo_dataset = grpo_dataset.train_test_split(test_size=0.1)

# Initialize GRPO trainer
trainer = GRPOTrainer(
    model=model,
    processing_class=tokenizer,
    reward_funcs=[hybrid_reward_function_with_llm_judge],
    args=training_args,
    train_dataset = grpo_dataset["train"],
    eval_dataset = grpo_dataset["test"],
)

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