---
id: pr-flash-attention-2470
repo: Dao-AILab/flash-attention
pr: 2470
title: '[Cute,Fwd,Sm100] Fix the crash when seqlen_k=0'
author: Johnsonms
date: '2026-04-20'
url: https://github.com/Dao-AILab/flash-attention/pull/2470
source_category: upstream-code
architectures:
- sm100
tags:
- cuda kernel
- cute
- sm100
- tma
techniques:
- async-copy
hardware_features:
- blackwell
- tma
kernel_types:
- attention
languages:
- cuda-cpp
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: 03cd0651b469fe3390b6b17fed1a7e9c23d32c91
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-2470
head_ref_oid: 589759750abc858046d5dbb32c1fed5809e3e87b
---
# [Cute,Fwd,Sm100] Fix the crash when seqlen_k=0

- Repository: `Dao-AILab/flash-attention`
- PR: [2470](https://github.com/Dao-AILab/flash-attention/pull/2470)
- 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-2470`
