---
id: pr-vllm-25851
repo: vllm-project/vllm
pr: 25851
title: '[Bugfix] Fallback ViT attn backend to SDPA for blackwell'
author: ywang96
date: '2025-09-29'
url: https://github.com/vllm-project/vllm/pull/25851
source_category: upstream-code
architectures:
- sm100
tags: []
techniques: []
hardware_features: []
kernel_types: []
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: 65ecb4f134a2a9b651c0ad070ad833cf6fe41b5b
inclusion_reason: defer
changed_paths:
- vllm/model_executor/models/qwen3_vl.py
- vllm/platforms/cuda.py
artifact_dir: evidence/pull-bundles/vllm/gh-25851
head_ref_oid: c1f7b19659788f6c168edfa4cad5d055613d98b7
---
# [Bugfix] Fallback ViT attn backend to SDPA for blackwell

- Repository: `vllm-project/vllm`
- PR: [25851](https://github.com/vllm-project/vllm/pull/25851)
- Decision: `defer`
- Reason: defer

## Changed Paths

- `vllm/model_executor/models/qwen3_vl.py`
- `vllm/platforms/cuda.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-25851`
