TST: fix `to` issue for 8-bit model #2797

yao-matrix · 2025-09-22T17:41:11Z

Issue

4 cases fail

pytest -rA tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit
pytest -rA tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_dora
pytest -rA tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5
pytest -rA tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit

w/ log

         raise ValueError(
                "`.to` is not supported for `8-bit` bitsandbytes models. Please use the model as it is, since the"
                " model has already been set to the correct devices and casted to the correct `dtype`."
E ValueError: .to is not supported for 8-bit bitsandbytes models. Please use the model as it is, since the model has already been set to the correct devices and casted to the correct dtype.

Root Cause

8-bit models don't support to and cuda according transformers logic

Fix

check whether model is loaded in 8 bit, and skip to if so.

Results:

Pass

@BenjaminBossan , pls help review, thx very much.

Signed-off-by: Yao, Matrix <[email protected]>

yao-matrix · 2025-09-23T21:31:49Z

@BenjaminBossan , could you pls take a review? Thx very much.

githubnemo · 2025-09-24T10:20:05Z

Thanks for the suggestion! I wonder if we should skip the test instead since we're "requesting" to use self.device but that model doesn't support using that device. WDYT?

Signed-off-by: Yao, Matrix <[email protected]>

yao-matrix · 2025-09-25T21:56:17Z

src/peft/utils/integrations.py

            weight = weight.to(torch.device("cuda"))
        elif is_xpu_available():
            weight = weight.to(torch.device("xpu"))
+            state.SCB = state.SCB.to(torch.device("xpu"))


weight is moved to accelerator, but SCB not, will make later int8_vectorwise_dequant cry to say weight in xpu, but SCB in cpu and make CPU CI, fail, so move it to accelerator too.

yao-matrix · 2025-09-25T21:56:36Z

src/peft/utils/integrations.py


    if is_cpu:
        dequantized = dequantized.to(device)
+        state.SCB = state.SCB.to(device)


both should be move back

yao-matrix · 2025-09-25T22:01:59Z

Thanks for the suggestion! I wonder if we should skip the test instead since we're "requesting" to use self.device but that model doesn't support using that device. WDYT?

@githubnemo, I took some time to dive into the issue and then cleaned the test cases, then the device cases passed, we have torch_device, device of class TestLoftQ, device through method arguments, kind of make the test case confused, so I cleaned it, then accelerator(xpu, cuda) case can pass.

for cpu failures, its because incomplete tensor transfer btw cpu and accelerator, i commented inline.

Thx very much for review and sorry for before's lazy workaround.

yao-matrix · 2025-09-29T15:55:37Z

@githubnemo , could you pls take a review again, thx very much

BenjaminBossan

Thanks for working on this with 8bit bnb and device placement. Unfortunately, when I run this locally, I still get errors:

$ CUDA_VISIBLE_DEVICES=0 pytest tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_dora tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5 tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit

FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit[cpu] - assert tensor(nan, grad_fn=<MeanBackward0>) > 0.0
FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_dora[cpu] - RuntimeError: invalid argument to getCurrentStream
FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5[cuda] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered
FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5[cpu] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered
FAILED tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit[cuda] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered
FAILED tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit[cpu] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered

I cannot test on XPU, but for CPU and CUDA, I get these errors. Do these tests pass for you?

Furthermore, I was wondering why these tests are not running on CI and I think it's a simple oversight, there is no test marker for TestLoftQ. Could you please add the @pytest.mark.single_gpu_tests decorator?

BenjaminBossan · 2025-09-30T12:52:38Z

tests/test_gpu_examples.py

+        # The error factor indicates by how much the quantization error should be decreased when using LoftQ compared to
+        # quantization without LoftQ. Thus 1.03 means that the error should be decreased by 3% at least. This is a very
+        # conservative value to prevent flakiness, in practice most gains are > 1.5
+        error_factor = 1.005 if device in ("xpu", "cpu") else 1.03


Did you find it necessary to reduce the factor to 1.005 for XPU and CPU?

currently, it's needed. We are continuing enhance bnb support, when it works, we can remove it.

I see. I checked again with CUDA/CPU and the improvement is much larger than 1.03 (which, as indicated, is a very conservative value to avoid flakiness). So if XPU is below that, I think it's an indicator that something is missing.

yao-matrix · 2025-09-30T21:47:50Z

Thanks for working on this with 8bit bnb and device placement. Unfortunately, when I run this locally, I still get errors:

$ CUDA_VISIBLE_DEVICES=0 pytest tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_dora tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5 tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit

FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit[cpu] - assert tensor(nan, grad_fn=<MeanBackward0>) > 0.0
FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_dora[cpu] - RuntimeError: invalid argument to getCurrentStream
FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5[cuda] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered
FAILED tests/test_gpu_examples.py::TestLoftQ::test_bloomz_loftq_8bit_iter_5[cpu] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered
FAILED tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit[cuda] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered
FAILED tests/test_gpu_examples.py::TestLoftQ::test_t5_loftq_8bit[cpu] - torch.AcceleratorError: CUDA error: an illegal memory access was encountered

I cannot test on XPU, but for CPU and CUDA, I get these errors. Do these tests pass for you?

Furthermore, I was wondering why these tests are not running on CI and I think it's a simple oversight, there is no test marker for TestLoftQ. Could you please add the @pytest.mark.single_gpu_tests decorator?

@BenjaminBossan Could you try installing latest bnb with pip install --force-reinstall https://github.com/bitsandbytes-foundation/bitsandbytes/releases/download/continuous-release_main/bitsandbytes-1.33.7.preview-py3-none-manylinux_2_24_x86_64.whl, since there is a bug in bnb and the fixing PR just merged bitsandbytes-foundation/bitsandbytes#1769. In my env, with this bnb fix, the test cases pass on XPU, CPU and CUDA(A100). Thx

Signed-off-by: Yao, Matrix <[email protected]>

HuggingFaceDocBuilderDev · 2025-10-01T09:08:41Z

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

BenjaminBossan

Thanks for fixing the 8bit bnb LoftQ tests and making LoftQ work with XPU, the PR LGTM.

The stuck CI is unrelated and can be ignored.

BenjaminBossan · 2025-10-01T10:01:27Z

tests/test_gpu_examples.py

+        # The error factor indicates by how much the quantization error should be decreased when using LoftQ compared to
+        # quantization without LoftQ. Thus 1.03 means that the error should be decreased by 3% at least. This is a very
+        # conservative value to prevent flakiness, in practice most gains are > 1.5
+        error_factor = 1.005 if device in ("xpu", "cpu") else 1.03


I see. I checked again with CUDA/CPU and the improvement is much larger than 1.03 (which, as indicated, is a very conservative value to avoid flakiness). So if XPU is below that, I think it's an indicator that something is missing.

This is to fix an oversight from huggingface#2797, where the LoftQ test was sligthly refactored but one test was not updated accordingly.

This is to fix an oversight from #2797, where the LoftQ test was sligthly refactored but one test was not updated accordingly.

Fixes some failing GPU tests in CI. A bug was introduced in huggingface#2797 where state.SCB was accessed while dequantizing 4bit bnb weights even though state is None. This would occur, for instance, when using DoRA, which needs to dequantize the weight. The attribute access is now restricted to 8bit bnb weights.

Fixes some failing GPU tests in CI. A bug was introduced in #2797 where state.SCB was accessed while dequantizing 4bit bnb weights even though state is None. This would occur, for instance, when using DoRA, which needs to dequantize the weight. The attribute access is now restricted to 8bit bnb weights.

fix to issue for 8-bit model

d7945d6

Signed-off-by: Yao, Matrix <[email protected]>

yao-matrix added 2 commits September 25, 2025 21:41

fix

2f17831

Signed-off-by: Yao, Matrix <[email protected]>

Update test_gpu_examples.py

489813f

yao-matrix commented Sep 25, 2025

View reviewed changes

Update integrations.py

092d262

matthewdouglas mentioned this pull request Sep 29, 2025

Linear8bitLt: support device movement after forward() bitsandbytes-foundation/bitsandbytes#1769

Merged

BenjaminBossan reviewed Sep 30, 2025

View reviewed changes

add mark

d43ebf4

Signed-off-by: Yao, Matrix <[email protected]>

BenjaminBossan approved these changes Oct 1, 2025

View reviewed changes

BenjaminBossan merged commit ffa971a into huggingface:main Oct 1, 2025
12 of 14 checks passed

yao-matrix deleted the issue-540 branch October 1, 2025 15:34

BenjaminBossan added a commit to BenjaminBossan/peft that referenced this pull request Oct 15, 2025

FIX TST Wrong attribute in LoftQ test

d076c99

This is to fix an oversight from huggingface#2797, where the LoftQ test was sligthly refactored but one test was not updated accordingly.

BenjaminBossan mentioned this pull request Oct 15, 2025

FIX TST Wrong attribute in LoftQ test #2841

Merged

BenjaminBossan added a commit that referenced this pull request Oct 15, 2025

FIX TST Wrong attribute in LoftQ test (#2841)

87b90f0

This is to fix an oversight from #2797, where the LoftQ test was sligthly refactored but one test was not updated accordingly.

BenjaminBossan mentioned this pull request Oct 17, 2025

FIX Bug when dequantizing 4bit bnb weights #2847

Merged

TST: fix to issue for 8-bit model #2797

TST: fix to issue for 8-bit model #2797

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TST: fix `to` issue for 8-bit model #2797

TST: fix `to` issue for 8-bit model #2797

yao-matrix commented Sep 22, 2025 •

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