fix: use no_mask in local ViT layer spec - #4395
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The local ViT layer spec incorrectly used AttnMaskType.causal while the TE spec uses AttnMaskType.no_mask. ViTs use bidirectional self-attention over image patches, so causal masking is incorrect. Commit 20abc85 ("fix vit mask") fixed this in the TE path but missed the local path. Fixes NVIDIA#1791 Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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/ok to test 5ab31f4 |
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@ericharper this is a test |
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🔄 Merge queue validation started! You can track the progress here: https://github.com/NVIDIA/Megatron-LM/actions/runs/25835211460 |
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Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com> Signed-off-by: Dmytro Pykhtar <dpykhtar@nvidia.com>
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Summary
AttnMaskType.causal→AttnMaskType.no_maskinget_vit_layer_with_local_spec()(megatron/core/models/vision/vit_layer_specs.py:72) to match the TE spec.Fixes #1791
Test plan
pretrain_vlm.pywith--transformer-impl localproduces correct ViT behaviortests/unit_tests/transformer/test_vision_cuda_graphs.py) still pass🤖 Generated with Claude Code