---
id: pr-flash-attention-2227
repo: Dao-AILab/flash-attention
pr: 2227
title: Nicer headdim error message
author: drisspg
date: '2026-03-09'
url: https://github.com/Dao-AILab/flash-attention/pull/2227
source_category: upstream-code
architectures:
- sm90
tags:
- sm90
techniques: []
hardware_features:
- hopper
kernel_types:
- attention
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: 0f375dd6a4c72441d5b05d1f572165bcf15b6c03
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- flash_attn/cute/interface.py
- tests/cute/test_flash_attn.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2227
head_ref_oid: 6c5eb889c86896704aa0ef589631eb98f5c290df
---
# Nicer headdim error message

- Repository: `Dao-AILab/flash-attention`
- PR: [2227](https://github.com/Dao-AILab/flash-attention/pull/2227)
- Decision: `Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.`
- Reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.

## Changed Paths

- `flash_attn/cute/interface.py`
- `tests/cute/test_flash_attn.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2227`
