---
id: pr-vllm-17283
repo: vllm-project/vllm
pr: 17283
title: '[BugFix] Fix cascade attention - RuntimeError: scheduler_metadata must have shape (metadata_size)'
author: LucasWilkinson
date: '2025-04-28'
url: https://github.com/vllm-project/vllm/pull/17283
source_category: upstream-code
architectures:
- sm100
tags:
- attention
techniques: []
hardware_features: []
kernel_types:
- attention
languages:
- python
captured_at: '2026-04-27'
status: merged
merge_sha: cc5befbced220b3bbb1a041a2d6aadd98472278d
inclusion_reason: kernel file changes
changed_paths:
- vllm/v1/attention/backends/flash_attn.py
head_ref_oid: 01e1540a4d559cd5bb9b865bdb6d5c13b153fc1e
artifact_dir: evidence/pull-bundles/vllm/gh-17283
---
# [BugFix] Fix cascade attention - RuntimeError: scheduler_metadata must have shape (metadata_size)

- Repository: `vllm-project/vllm`
- PR: [17283](https://github.com/vllm-project/vllm/pull/17283)
- Decision: `kernel file changes`
- Reason: kernel file changes

## Changed Paths

- `vllm/v1/attention/backends/flash_attn.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-17283`
