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[BugFix][DeepSeek-V3.2] Fix backend selection logic for Blackwell #30195

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LucasWilkinson merged 1 commit into from
Dec 7, 2025
Merged

[BugFix][DeepSeek-V3.2] Fix backend selection logic for Blackwell #30195

LucasWilkinson merged 1 commit into from
Dec 7, 2025

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@LucasWilkinson LucasWilkinson commented Dec 7, 2025 •
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Fix

ValueError: Selected backend AttentionBackendEnum.CUTLASS_MLA is not valid for this configuration. Reason: ['kv_cache_dtype not supported', 'sparse not supported']

When running

vllm serve deepseek-ai/DeepSeek-V3.2

on 8xB200

@LucasWilkinson
fix selection logic
28d5086 
Signed-off-by: Lucas Wilkinson <[email protected]>
@LucasWilkinson LucasWilkinson requested a review from mgoin December 7, 2025 05:47
@mergify mergify bot added deepseek Related to DeepSeek models nvidia labels Dec 7, 2025
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Code Review

The code was updated to prevent forcing CutlassMLA for Blackwell GPUs when sparse attention (specifically DSv3.2) is enabled, by adding a not use_sparse condition to the relevant configuration check.

houseroad
houseroad approved these changes Dec 7, 2025
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Thanks for the fix.

@github-project-automation github-project-automation bot moved this to In review in NVIDIA Dec 7, 2025
@mgoin mgoin added the ready ONLY add when PR is ready to merge/full CI is needed label Dec 7, 2025
@LucasWilkinson LucasWilkinson merged commit 0044c40 into vllm-project:main Dec 7, 2025
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@github-project-automation github-project-automation bot moved this from In review to Done in NVIDIA Dec 7, 2025
penfree pushed a commit to penfree/vllm that referenced this pull request Dec 8, 2025
@LucasWilkinson
[BugFix][DeepSeek-V3.2] Fix backend selection logic for Blackwell (vl…
eeaacdd 
…lm-project#30195)
@LucasWilkinson LucasWilkinson mentioned this pull request Dec 8, 2025
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@mgoin mgoin mgoin approved these changes

@houseroad houseroad houseroad approved these changes

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