[https://nvbugs/6336801][fix] Add the two skip_softmax_threshold_scale_factor_decode/prefill aliases to…

[tensorrt-cicd]

Summary

• Root cause: Sync allowlists drifted: _THOP_KWARG_SOURCE_ALIASES missed two new skip_softmax_threshold_scale_factor_* aliases added by PR [TRTLLM-12807][feat] Add multiple FMHA library support to TRTLLM attention backend #15204, and _THOP_EXCLUDED_FIELDS missed multi_item_part_lens (added to AttentionForwardArgs by PR [TRTLLM-12982][feat] support multi item scoring in LLM.encode #14693 but rejected upstream by TrtllmAttention.forward, never reaching the FallbackFmha thop call).
• Fix: Add the two skip_softmax_threshold_scale_factor_decode/prefill aliases to _THOP_KWARG_SOURCE_ALIASES in the test file, and add multi_item_part_lens to _THOP_EXCLUDED_FIELDS in fallback.py (mirroring topk_indices/out_scale_sf which other backends consume but the thop fallback does not).
• Automated fix generated by repair-bot

Test plan

• Verify fix on the same GPU type as the original failure
• Check for regressions in related tests

Links

• Bug: https://nvbugs/6336801

Summary by CodeRabbit

• Chores
  • Updated attention backend field handling and exclusion configurations.
  • Enhanced test validation for attention operation parameter mappings to ensure proper configuration coverage.

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📥 Commits

Reviewing files that changed from the base of the PR and between 4a8b7af and b484068.

⛔ Files ignored due to path filters (1)

• tests/integration/defs/examples/visual_gen/golden/visual_gen_lpips/visual_gen_lpips_golden_media.zip is excluded by !**/*.zip

📒 Files selected for processing (2)

• tensorrt_llm/_torch/attention_backend/fmha/fallback.py
• tests/unittest/_torch/attention_backend/test_attention_op_sync.py

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📝 Walkthrough

Walkthrough

Two allowlists for the thop.attention synchronization check are extended: the fallback FMHA backend's _THOP_EXCLUDED_FIELDS gains "multi_item_part_lens", and the sync test's _THOP_KWARG_SOURCE_ALIASES gains two explicit mappings for skip_softmax_threshold_scale_factor_decode and skip_softmax_threshold_scale_factor_prefill to their SkipSoftmaxKernelParams source attributes.

Changes

thop Attention Sync Allowlist Extensions

Layer / File(s)	Summary
Excluded-fields and kwarg-alias allowlist additions tensorrt_llm/_torch/attention_backend/fmha/fallback.py, tests/unittest/_torch/attention_backend/test_attention_op_sync.py	_THOP_EXCLUDED_FIELDS adds "multi_item_part_lens" to exempt it from required kwarg/property mapping; _THOP_KWARG_SOURCE_ALIASES adds two entries mapping skip_softmax_threshold_scale_factor_decode/prefill kwargs to SkipSoftmaxKernelParams.threshold_scale_factor_decode/prefill attributes.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• NVIDIA/TensorRT-LLM#15204: Directly related — this PR extends the same _THOP_EXCLUDED_FIELDS and fallback FMHA sync machinery introduced or refactored in that PR.
• NVIDIA/TensorRT-LLM#15335: Directly related — this PR adds further entries to the same _THOP_KWARG_SOURCE_ALIASES allowlist that was introduced/modified in that PR.

Suggested reviewers

• DanBlanaru
• bobboli
• QiJune
• yihwang-nv

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the fix addressing the missing aliases referenced in bug 6336801, matching the main changes in the changeset.
Description check	✅ Passed	The description provides clear context on the root cause, the fix applied, and test validation, but lacks explicit mapping to PR checklist items.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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