---
id: pr-flash-attention-2496
repo: Dao-AILab/flash-attention
pr: 2496
title: '[CuTe,Flex] Add score_mod_bwd param to flash_attn_varlen_func'
author: reubenconducts
date: '2026-04-26'
url: https://github.com/Dao-AILab/flash-attention/pull/2496
source_category: upstream-code
architectures:
- sm100
tags:
- attention
- cute
techniques: []
hardware_features: []
kernel_types:
- attention
languages:
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: c9a560f44002da92d82680036e3482d0ac4939a3
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- flash_attn/cute/interface.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2496
head_ref_oid: 43025f103bcc266da7770ba9477813669b5e34f7
---
# [CuTe,Flex] Add score_mod_bwd param to flash_attn_varlen_func

- Repository: `Dao-AILab/flash-attention`
- PR: [2496](https://github.com/Dao-AILab/flash-attention/pull/2496)
- 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`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2496`
