---
id: pr-flash-attention-2091
repo: Dao-AILab/flash-attention
pr: 2091
title: Fix IMA in fwd on m boundary
author: drisspg
date: '2025-12-20'
url: https://github.com/Dao-AILab/flash-attention/pull/2091
source_category: upstream-code
architectures:
- sm100
tags:
- arch_pipeline
- attention_kv
- benchmark_test
- block sparse
- compiler_runtime
techniques:
- pipeline-stages
hardware_features:
- blackwell
kernel_types:
- attention
- compiler
- runtime
languages:
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: bba578d43974c1d3ba157ab597124dd0fe2ccdb4
inclusion_reason: Mine shape sets, tolerance rules, warmup logic, and profile commands before mutating code.
changed_paths:
- flash_attn/cute/block_sparse_utils.py
- flash_attn/cute/flash_bwd_sm100.py
- flash_attn/cute/flash_fwd_sm100.py
- flash_attn/cute/mask.py
- tests/cute/test_mask_mod.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2091
head_ref_oid: d3c2643e6066cb201536482458a5d5de2f5fadb8
---
# Fix IMA in fwd on m boundary

- Repository: `Dao-AILab/flash-attention`
- PR: [2091](https://github.com/Dao-AILab/flash-attention/pull/2091)
- Decision: `Mine shape sets, tolerance rules, warmup logic, and profile commands before mutating code.`
- Reason: Mine shape sets, tolerance rules, warmup logic, and profile commands before mutating code.

## Changed Paths

- `flash_attn/cute/block_sparse_utils.py`
- `flash_attn/cute/flash_bwd_sm100.py`
- `flash_attn/cute/flash_fwd_sm100.py`
- `flash_attn/cute/mask.py`
- `tests/cute/test_mask_mod.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2091`
