多机多卡 sft Qwen3-VL-8B时同时开启sequence_parallel_size和enable_channel_loss时报错

[pingpingpangpang]

Describe the bug
多机多卡 sft Qwen3-VL-8B时同时开启sequence_parallel_size和enable_channel_loss时报错：

  [rank7]: Traceback (most recent call last):
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/cli/sft.py", line 20, in <module>
  [rank7]:     sft_main()
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/train/sft.py", line 364, in sft_main
  [rank7]:     return SwiftSft(args).main()
  [rank7]:            ^^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/base.py", line 49, in main
  [rank7]:     result = self.run()
  [rank7]:              ^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/ray/base.py", line 170, in wrapper
  [rank7]:     return func(self, *args, **kwargs)
  [rank7]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/train/sft.py", line 209, in run
  [rank7]:     return self.train(trainer)
  [rank7]:            ^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/train/sft.py", line 257, in train
  [rank7]:     trainer.train(trainer.args.resume_from_checkpoint)
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/trainers/mixin.py", line 841, in train
  [rank7]:     res = super().train(*args, **kwargs)
  [rank7]:           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/env/conda/envs/ms-swift-3.11.1/lib/python3.11/site-packages/transformers/trainer.py", line 2325, in train
  [rank7]:     return inner_training_loop(
  [rank7]:            ^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/env/conda/envs/ms-swift-3.11.1/lib/python3.11/site-packages/transformers/trainer.py", line 2674, in _inner_training_loop
  [rank7]:     tr_loss_step = self.training_step(model, inputs, num_items_in_batch)
  [rank7]:                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/trainers/trainers.py", line 420, in training_step
  [rank7]:     return super().training_step(model, inputs, *args, **kwargs)
  [rank7]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/env/conda/envs/ms-swift-3.11.1/lib/python3.11/site-packages/transformers/trainer.py", line 4020, in training_step
  [rank7]:     loss = self.compute_loss(model, inputs, num_items_in_batch=num_items_in_batch)
  [rank7]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank7]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/trainers/trainers.py", line 376, in compute_loss
  [rank7]:     metrics[f'loss_{channel}'].update(outputs.loss[slice_][masks[slice_]])
  [rank7]:                                       ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  [rank7]: IndexError: The shape of the mask [1] at index 0 does not match the shape of the indexed tensor [2903] at index 0
  [rank3]: Traceback (most recent call last):
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/cli/sft.py", line 20, in <module>
  [rank3]:     sft_main()
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/train/sft.py", line 364, in sft_main
  [rank3]:     return SwiftSft(args).main()
  [rank3]:            ^^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/base.py", line 49, in main
  [rank3]:     result = self.run()
  [rank3]:              ^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/ray/base.py", line 170, in wrapper
  [rank3]:     return func(self, *args, **kwargs)
  [rank3]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/train/sft.py", line 209, in run
  [rank3]:     return self.train(trainer)
  [rank3]:            ^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/llm/train/sft.py", line 257, in train
  [rank3]:     trainer.train(trainer.args.resume_from_checkpoint)
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/trainers/mixin.py", line 841, in train
  [rank3]:     res = super().train(*args, **kwargs)
  [rank3]:           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/env/conda/envs/ms-swift-3.11.1/lib/python3.11/site-packages/transformers/trainer.py", line 2325, in train
  [rank3]:     return inner_training_loop(
  [rank3]:            ^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/env/conda/envs/ms-swift-3.11.1/lib/python3.11/site-packages/transformers/trainer.py", line 2674, in _inner_training_loop
  [rank3]:     tr_loss_step = self.training_step(model, inputs, num_items_in_batch)
  [rank3]:                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/trainers/trainers.py", line 420, in training_step
  [rank3]:     return super().training_step(model, inputs, *args, **kwargs)
  [rank3]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/env/conda/envs/ms-swift-3.11.1/lib/python3.11/site-packages/transformers/trainer.py", line 4020, in training_step
  [rank3]:     loss = self.compute_loss(model, inputs, num_items_in_batch=num_items_in_batch)
  [rank3]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [rank3]:   File "/cpfs/shared/L4-new/VLM/dxb/code/ms-swift-3.11.1/swift/trainers/trainers.py", line 376, in compute_loss
  [rank3]:     metrics[f'loss_{channel}'].update(outputs.loss[slice_][masks[slice_]])
  [rank3]:                                       ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  [rank3]: IndexError: The shape of the mask [2383] at index 0 does not match the shape of the indexed tensor [1, 49140] at index 0

训练脚本如下：

CUDA_VISIBLE_DEVICES=0,1,2,3,4,5,6,7 \
NNODES=2 \
NODE_RANK=0 \
MASTER_ADDR=xx.xx.xx.xx \
MASTER_PORT=29501 \
NPROC_PER_NODE=8 \
swift sft \
    --model Qwen3-VL-8B-Instruct \
    --train_type full \
    --dataset 'test.jsonl' \
    --load_from_cache_file false \
    --torch_dtype bfloat16 \
    --num_train_epochs 1 \
    --per_device_train_batch_size 2 \
    --per_device_eval_batch_size 2 \
    --learning_rate 1e-5 \
    --gradient_accumulation_steps 1 \
    --eval_steps 100 \
    --save_steps 100 \
    --save_total_limit 2 \
    --logging_steps 1 \
    --output_dir output \
    --system 'You are a helpful assistant.' \
    --warmup_ratio 0.05 \
    --dataloader_num_workers 8 \
    --attn_impl flash_attn \
    --ddp_backend nccl \
    --dataset_num_proc 8 \
    --packing true \
    --max_length 24576 \
    --dataloader_pin_memory false \
    --sequence_parallel_size 2 \
    --save_only_model true \
    --deepspeed zero3 \
    --enable_channel_loss true \

Your hardware and system info
Write your system info like CUDA version/system/GPU/torch version here(在这里给出硬件信息和系统信息，如```
CUDA版本，系统，GPU型号和torch版本等)

两台机器共16张A100显卡
ubuntu22.04系统、cuda12.2、torch2.8.0
ms-swift3.11.1

Additional context
Add any other context about the problem here(在这里补充其他信息)

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