save_state removes shared weights but load_state cannot load properly

[MiladInk]

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System Info

accelerate version: 0.27.2
python: 3.11

Information

• [ ] The official example scripts
• [X] My own modified scripts

Tasks

• [ ] One of the scripts in the examples/ folder of Accelerate or an officially supported no_trainer script in the examples folder of the transformers repo (such as run_no_trainer_glue.py)
• [X] My own task or dataset (give details below)

Reproduction

I am saving the state_dict of an 'facebook/opt-125m' model. In this model the weights are shared between embedding tokens and the language modelling head. When I am saving the state dictionary of the model, I see this warning:

WARNING: Removed shared tensor {'pretrained_model.lm_head.weight'} while saving. This should be OK, but check by verifying that you don't receive any warning while reloading

The problem is when I want to load_state the same object, there is an error that:

Missing key(s) in state_dict: "pretrained_model.lm_head.weight". 

I do understand that because the weights are shared they are removed, but I don't understand how can I work with models which have shared weights then?

Interesting thing is, the code was working with the previous versions of the libraries. Unfortunately, I don't have the old environment to tell you exactly where things break.

Thanks in advance.

Expected behavior

I expected the save_state and load_state to be able to restore the original model no matter what. This does not work.

[muellerzr]

cc @SunMarc

[SunMarc]

Hi @MiladInk, thanks for the report. Could you share a minimal reproducer ? When we load a model with shared weights, we make sure to tie the shared weights together.

[raghavgarg97]

I am facing a similar issue when trying to load and save “google/gemma-2b”

[SunMarc]

Hi @raghavgarg97, could you share a minimal reproducer ?

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