Skip to content

[Bugfix] Fix bnb 8bit model weights loading #19917

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jun 21, 2025

Conversation

Isotr0py
Copy link
Collaborator

@Isotr0py Isotr0py commented Jun 20, 2025

Essential Elements of an Effective PR Description Checklist

  • The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
  • The test plan, such as providing test command.
  • The test results, such as pasting the results comparison before and after, or e2e results
  • (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

Purpose

[rank0]:   File "/kaggle/working/vllm/vllm/model_executor/model_loader/__init__.py", line 59, in get_model
[rank0]:     return loader.load_model(vllm_config=vllm_config,
[rank0]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[rank0]:   File "/kaggle/working/vllm/vllm/model_executor/model_loader/base_loader.py", line 41, in load_model
[rank0]:     self.load_weights(model, model_config)
[rank0]:   File "/kaggle/working/vllm/vllm/model_executor/model_loader/bitsandbytes_loader.py", line 547, in load_weights
[rank0]:     dequantize_dq(quant_states)
[rank0]:   File "/kaggle/working/vllm/vllm/model_executor/model_loader/bitsandbytes_loader.py", line 583, in dequantize_dq
[rank0]:     if quant_state.nested:
[rank0]:        ^^^^^^^^^^^^^^^^^^
[rank0]: AttributeError: 'Tensor' object has no attribute 'nested'. Did you mean: 'is_nested'?

Test Plan

python examples/offline_inference/basic/generate.py --model JohnConnor123/Llama-3.2-3B-Instruct-BNB-8bit --max-model-len 1024
pytest -s -v tests/quantization/test_bitsandbytes.py -k test_load_8bit_bnb_model

Test Result

The offline generation should run successfully and bnb 8bit tests should pass now.

(Optional) Documentation Update

Signed-off-by: Isotr0py <2037008807@qq.com>
@Isotr0py Isotr0py requested a review from jeejeelee June 20, 2025 17:35
Copy link
Contributor

@gemini-code-assist gemini-code-assist bot left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Summary of Changes

Hello @Isotr0py, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request provides a critical bug fix for loading BitsAndBytes (BNB) 8-bit quantized models, which previously failed due to a type mismatch during the dequantization process. The change ensures robust model loading by adding a necessary type check, thereby restoring compatibility and functionality for these models.

Highlights

  • Bugfix: Addressed an AttributeError that occurred when loading BitsAndBytes (BNB) 8-bit pre-quantized models. The error, AttributeError: 'Tensor' object has no attribute 'nested', was resolved by ensuring that the quant_state object is an instance of QuantState before attempting to access its nested attribute.
Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature Command Description
Code Review /gemini review Performs a code review for the current pull request in its current state.
Pull Request Summary /gemini summary Provides a summary of the current pull request in its current state.
Comment @gemini-code-assist Responds in comments when explicitly tagged, both in issue comments and review comments.
Help /gemini help Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist is currently in preview and may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments to provide feedback.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

  1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution.

Copy link
Contributor

@gemini-code-assist gemini-code-assist bot left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Code Review

This pull request effectively addresses a critical bug that caused an AttributeError when loading BNB 8-bit pre-quantized models. The error occurred because the dequantize_dq function attempted to access a .nested attribute on a torch.Tensor object, which was not always a bitsandbytes.functional.QuantState instance as expected.

The fix introduces a type check using isinstance(quant_state, QuantState) before accessing the .nested attribute. This ensures that the attribute is only accessed if quant_state is indeed a QuantState object, thereby preventing the crash. The necessary QuantState import has also been correctly added.

The change is well-targeted and directly resolves the reported issue, improving the robustness of the bitsandbytes model loader.

Copy link

👋 Hi! Thank you for contributing to the vLLM project.

💬 Join our developer Slack at https://slack.vllm.ai to discuss your PR in #pr-reviews, coordinate on features in #feat- channels, or join special interest groups in #sig- channels.

Just a reminder: PRs would not trigger full CI run by default. Instead, it would only run fastcheck CI which starts running only a small and essential subset of CI tests to quickly catch errors. You can run other CI tests on top of those by going to your fastcheck build on Buildkite UI (linked in the PR checks section) and unblock them. If you do not have permission to unblock, ping simon-mo or khluu to add you in our Buildkite org.

Once the PR is approved and ready to go, your PR reviewer(s) can run CI to test the changes comprehensively before merging.

To run CI, PR reviewers can either: Add ready label to the PR or enable auto-merge.

🚀

Copy link
Collaborator

@jeejeelee jeejeelee left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks for this fixing

@jeejeelee jeejeelee added the ready ONLY add when PR is ready to merge/full CI is needed label Jun 21, 2025
@jeejeelee jeejeelee enabled auto-merge (squash) June 21, 2025 00:13
@jeejeelee jeejeelee merged commit 6f170f1 into vllm-project:main Jun 21, 2025
81 checks passed
@Isotr0py Isotr0py deleted the fix-bnb-8bit branch June 21, 2025 03:41
@Isotr0py Isotr0py restored the fix-bnb-8bit branch June 21, 2025 04:23
@Isotr0py Isotr0py deleted the fix-bnb-8bit branch June 21, 2025 04:23
yeqcharlotte pushed a commit to yeqcharlotte/vllm that referenced this pull request Jun 22, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
juncheoll pushed a commit to juncheoll/vllm that referenced this pull request Jun 23, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
Signed-off-by: juncheoll <th6re8e@naver.com>
fhl2000 pushed a commit to fhl2000/vllm that referenced this pull request Jun 25, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
Signed-off-by: fhl <2410591650@qq.com>
gmarinho2 pushed a commit to gmarinho2/vllm that referenced this pull request Jun 26, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
xjpang pushed a commit to xjpang/vllm that referenced this pull request Jun 30, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
wseaton pushed a commit to wseaton/vllm that referenced this pull request Jun 30, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
Signed-off-by: Will Eaton <weaton@redhat.com>
wseaton pushed a commit to wseaton/vllm that referenced this pull request Jun 30, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
wwl2755-google pushed a commit to wwl2755-google/vllm that referenced this pull request Jul 1, 2025
Signed-off-by: Isotr0py <2037008807@qq.com>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
ready ONLY add when PR is ready to merge/full CI is needed
Projects
None yet
Development

Successfully merging this pull request may close these issues.

2 participants