sgl-project/sglang

[Bug] flashinfer gdn kernel not working

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#21,085 opened on Mar 21, 2026

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good first issue

Description

Checklist

  • I searched related issues but found no solution.
  • The bug persists in the latest version.
  • Issues without environment info and a minimal reproducible demo are hard to resolve and may receive no feedback.
  • If this is not a bug report but a general question, please start a discussion at https://github.com/sgl-project/sglang/discussions. Otherwise, it will be closed.
  • Please use English. Otherwise, it will be closed.

Describe the bug

It keeps breaking ci on blackwell. So we have to ignore it in https://github.com/sgl-project/sglang/pull/21081/changes

After fixing it, we should reenable this test.

Reproduction

python test/registered/4-gpu-models/test_qwen35_models.py

Environment

install from latest main

Contributor guide

Tech stack
pythoncpp
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
PythonCUDAGPU programming
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate the flashinfer gdn kernel implementation and the failing test to identify why it fails on blackwell GPUs. Check the PR #21081 for context on the skipped test and ensure the fix reenables it.