[Feature]: Composite model loading using `AutoWeightsLoader` for all models

[DarkLight1337]

🚀 The feature, motivation and pitch

#9160 first introduced AutoWeightsLoader to recursively call load_weights on sub-modules. This lets composite models (most notably multi-modal models) use language backbones (*Model classes such as LlamaModel) without having to repeat their weight loading logic.

Currently, load_weights is only implemented in a few language backbones. It would be great to standardize this approach and apply it to all language backbones in vLLM. The steps to do this are pretty straightforward:

1. Move the existing load_weights function from *ForCausalLM to *Model.
2. Create a new load_weights function in *ForCausalLM that loads the weights using AutoWeightsLoader.
3. Move any logic in *Model.load_weights that only applies to *ForCausalLM back to *ForCausalLM.load_weights. Usually, this involves lm_head.

For reference, you can look at the implementation for models such as Llama, Gemma2/3, Qwen2 and ChatGLM.

To avoid scope creep, I suggest opening a PR for updating only a few models at a time

Alternatives

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Additional context

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[lengrongfu]

@DarkLight1337 I can try to process several models

[DarkLight1337]

Can you indicate which models you are working on to avoid others duplicating your work?

[lengrongfu]

I haven't started yet, do you have any recommendations for simpler models?

[DarkLight1337]

Most language models should work in pretty much the same way (except SSMs like Mamba I guess). You can go in alphabetical order.

[lengrongfu]

Thanks ~
/assign

[lengrongfu]

Tips, these are unimplemented models, i use shell script to count, this is the approximate result：

• arctic.py
• baichuan.py
• bamba.py
• bart.py
• bert.py
• bloom.py
• clip.py
• chameleon.py
• commandr.py
• dbrx.py
• deepseek.py
• deepseek_v2.py
• exaone.py
• falcon.py
• gemma.py
• glm.py
• glm4.py
• gpt2.py
• gpt_bigcode.py
• gpt_j.py
• gpt_neox.py
• granite.py
• granitemoe.py
• granitemoeshared.py
• gritlm.py
• grok1.py
• h2ovl.py
• idefics2_vision_model.py
• interfaces.py
• interfaces_base.py
• internlm2.py
• jais.py
• jamba.py
• mamba.py
• mamba2.py
• mamba_cache.py
• medusa.py
• minicpm3.py
• mixtral.py
• mixtral_quant.py
• mllama.py
• module_mapping.py
• mpt.py
• nemotron.py
• nemotron_nas.py
• nvlm_d.py
• olmo.py
• olmo2.py
• olmoe.py
• opt.py
• orion.py
• persimmon.py
• phi.py
• phi3.py
• phi3_small.py
• phi4mm_audio.py
• phi4mm_utils.py
• phimoe.py
• pixtral.py
• qwen.py
• qwen2_moe.py
• qwen3_moe.py
• qwen_vl.py
• registry.py
• roberta.py
• siglip.py
• solar.py
• stablelm.py
• starcoder2.py
• teleflm.py
• vision.py
• zamba2.py

[DarkLight1337]

The multi-modal models don't need this change, can you remove them from the list?

[jonghyunchoe]

Hi, I could take on a few models, e.g. baichuan, gpt_neox, and mpt.