---
id: pr-flash-attention-2026
repo: Dao-AILab/flash-attention
pr: 2026
title: '[Cute,Fwd,Sm100] don''t pass mask_fn to softmax_step generically'
author: jayhshah
date: '2025-11-22'
url: https://github.com/Dao-AILab/flash-attention/pull/2026
source_category: upstream-code
architectures:
- sm100
tags:
- arch_pipeline
- attention_kv
- compiler_runtime
- softmax
techniques:
- async-copy
- pipeline-stages
hardware_features:
- blackwell
- tma
kernel_types:
- attention
- compiler
- runtime
- softmax
languages:
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: d063b333baae9c6066fe003be18c426eb602cbf3
inclusion_reason: 'Extract the architecture assumption first: SM target, TMA/WGMMA/tcgen path, cluster use, and pipeline stages.'
changed_paths:
- flash_attn/cute/flash_fwd_sm100.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2026
head_ref_oid: 47de685ca78e8c3e4470627a4e349823fa985963
---
# [Cute,Fwd,Sm100] don't pass mask_fn to softmax_step generically

- Repository: `Dao-AILab/flash-attention`
- PR: [2026](https://github.com/Dao-AILab/flash-attention/pull/2026)
- Decision: `Extract the architecture assumption first: SM target, TMA/WGMMA/tcgen path, cluster use, and pipeline stages.`
- Reason: Extract the architecture assumption first: SM target, TMA/WGMMA/tcgen path, cluster use, and pipeline stages.

## Changed Paths

- `flash_attn/cute/flash_fwd_sm100.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2026`
