version-compat CI: fake CPU training runs for SFT/GRPO/DPO (#6965)

* version-compat CI: fake CPU training runs for SFT/GRPO/DPO

Adds a runtime layer on top of the patch-run canary: actually runs
trainer.train() for a couple of steps on a CPU-only runner under the CUDA
spoof, wrapping a plain tiny HF model in the Unsloth-patched trainer. Exercises
the real train() loop (collation, generation, the injected
_get_per_token_logps_and_entropies, loss, backward, optimizer) so a TRL or
transformers change that breaks the loop at runtime -- not just the source
structure -- surfaces here. No GPU, no meaningful numerics.

Needs a chain of small CPU shims (eager torch.compile, dynamo suppress, cuda
tensor-alloc redirect to CPU, model.for_training/for_inference equivalents)
documented inline. Does not exercise Unsloth's Triton/GPU kernels (CPU can't).

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* cpu fake-train: force adamw_torch + disable dynamo for CPU runner

On a real CPU-build torch runner (GitHub CI) two things bit that a CUDA-build
torch with GPUs hidden masked locally:

- The default optimizer is adamw_8bit (bitsandbytes), whose is_on_gpu() check
  dies on CPU tensors. Force optim=adamw_torch in all three configs.
- import unsloth reinstalls the real torch.compile over the eager passthrough,
  so the GRPO hot path (chunked_selective_log_softmax) actually compiles and
  inductor picks the spoofed CUDA device, crashing on device props
  (gcnArchName). Re-apply the eager passthrough after import and flip
  torch._dynamo.config.disable so every @torch.compile runs eager at call time.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* cpu fake-train: write checkpoints under pytest tmp_path

Use pytest's tmp_path for each trainer's output_dir instead of a hardcoded
relative temp/ci_* path, so a local pytest run does not leave untracked dirs in
the repo tree and the tests are CWD-independent.

* version-compat CI: disable dynamo at process level for the fake-run job

Set TORCHDYNAMO_DISABLE / TORCH_COMPILE_DISABLE in the fake-run step env so
dynamo/inductor is off before conftest.py's early import unsloth, not only via
the per-test runtime shim. Defense in depth on the GPU-less runner: the GRPO
hot path never compiles regardless of when its functions were decorated.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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Daniel Han 2026-07-08 04:06:28 -07:00 committed by GitHub
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@ -339,12 +339,18 @@ jobs:
env:
UNSLOTH_IS_PRESENT: '1'
UNSLOTH_COMPILE_DISABLE: '1'
# Disable dynamo/inductor at the process level, before conftest.py's early
# `import unsloth`, so the GRPO hot path never compiles on the GPU-less runner
# (defense in depth; the CPU fake-train also flips this at runtime).
TORCHDYNAMO_DISABLE: '1'
TORCH_COMPILE_DISABLE: '1'
PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION: python
run: |
cd unsloth
python -c "import trl; print('Resolved TRL', trl.__version__)"
PYTHONPATH=. python -m pytest \
tests/version_compat/test_trl_grpo_fake_run.py \
tests/version_compat/test_trl_fake_train_cpu.py \
-v --tb=short
# `main` is scheduled/dispatch-only so PR jobs stay fast and a bleeding-edge
# TRL break does not red every PR. github.event_name is valid in a step if.
@ -353,6 +359,8 @@ jobs:
env:
UNSLOTH_IS_PRESENT: '1'
UNSLOTH_COMPILE_DISABLE: '1'
TORCHDYNAMO_DISABLE: '1'
TORCH_COMPILE_DISABLE: '1'
PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION: python
run: |
pip install --upgrade "git+https://github.com/huggingface/trl"
@ -360,6 +368,7 @@ jobs:
python -c "import trl; print('Resolved TRL', trl.__version__)"
PYTHONPATH=. python -m pytest \
tests/version_compat/test_trl_grpo_fake_run.py \
tests/version_compat/test_trl_fake_train_cpu.py \
-v --tb=short
# Daily-only: same suites but with --strict on importable upstream

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@ -0,0 +1,285 @@
# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team.
"""Fake CPU training runs for the Unsloth-patched SFT / GRPO / DPO trainers.
The patch-run canary (test_trl_grpo_fake_run.py) only compiles + inspects the
generated trainer source. This goes one layer deeper: it actually runs
`trainer.train()` for a couple of steps on a CPU-only runner, under the CUDA
spoof, wrapping a plain (tiny, random-weight) HF model in the Unsloth-patched
trainer. That exercises the real train() loop at runtime -- data collation,
generation (GRPO), the injected `_get_per_token_logps_and_entropies`, loss,
backward, optimizer -- so a TRL or transformers change that breaks the loop
(not just the source structure) surfaces here. No GPU, no meaningful numerics.
What it does NOT cover: Unsloth's Triton/GPU-optimized model kernels (the
FastLanguageModel fast path) cannot run on CPU, so this validates the
trainer-transform + orchestration layer with a standard forward, not the
optimized kernels.
"""
from __future__ import annotations
import os
# CPU-only: no torch.compile / dynamo (it reaches into the CUDA accelerator), no
# Unsloth kernel compile, no mixed precision. Must be set before torch/unsloth.
os.environ.setdefault("UNSLOTH_COMPILE_DISABLE", "1")
os.environ.setdefault("TORCHDYNAMO_DISABLE", "1")
os.environ.setdefault("TORCH_COMPILE_DISABLE", "1")
os.environ.setdefault("ACCELERATE_MIXED_PRECISION", "no")
import importlib
import importlib.util
import sys
from pathlib import Path
import pytest
# torch is needed for everything below (daily-fresh-fetch collects this dir with
# only pytest installed); skip the whole module cleanly when it is absent.
if importlib.util.find_spec("torch") is None:
pytest.skip(
"torch not installed; fake CPU train needs the real runtime", allow_module_level = True
)
# Apply the CUDA spoof before any unsloth-touching import.
_SPOOF_DIR = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(_SPOOF_DIR))
import _zoo_aggressive_cuda_spoof as _spoof # noqa: E402
_spoof.apply()
import torch # noqa: E402
# The generated GRPO trainer hard-decorates hot functions with @torch.compile,
# which dynamo processes even under the disable env vars, reaching into
# torch.accelerator (real CUDA) on a GPU-less box. Make torch.compile an eager
# passthrough before unsloth generates/imports the trainer -- same logic, no
# dynamo. (An eager CPU run is exactly what we want here.)
def _eager_compile(
model = None,
*args,
**kwargs,
):
if callable(model):
return model
return lambda fn: fn
torch.compile = _eager_compile
# Belt-and-suspenders: if any @torch.compile still routes through dynamo, let it
# fall back to eager instead of crashing, and stop its stream-capture probe from
# reaching torch.accelerator -> real CUDA on a GPU-less box.
try:
import torch._dynamo # noqa: E402
torch._dynamo.config.suppress_errors = True
except Exception:
pass
if hasattr(torch, "accelerator"):
torch.accelerator.is_available = lambda *a, **k: False
# Redirect any `device="cuda"` tensor allocation / `.to("cuda")` / `.cuda()` to
# CPU. The aggressive spoof deliberately keeps real allocators, but a fake CPU
# train needs cuda-targeted ops (e.g. inductor's init_gpu_context does
# `torch.empty(1, device="cuda")`) to land on CPU instead of erroring.
def _is_cuda_dev(d):
try:
return d is not None and torch.device(d).type == "cuda"
except Exception:
return False
for _name in (
"empty",
"zeros",
"ones",
"full",
"tensor",
"arange",
"randn",
"rand",
"randint",
"empty_like",
"zeros_like",
"ones_like",
):
_orig = getattr(torch, _name, None)
if _orig is None:
continue
def _redir(
*args,
_orig = _orig,
**kwargs,
):
if _is_cuda_dev(kwargs.get("device")):
kwargs["device"] = "cpu"
return _orig(*args, **kwargs)
setattr(torch, _name, _redir)
_orig_to = torch.Tensor.to
def _to_cpu(self, *args, **kwargs):
args = tuple("cpu" if _is_cuda_dev(a) else a for a in args)
if _is_cuda_dev(kwargs.get("device")):
kwargs["device"] = "cpu"
return _orig_to(self, *args, **kwargs)
torch.Tensor.to = _to_cpu
torch.Tensor.cuda = lambda self, *a, **k: self
# Extra CUDA stubs the aggressive spoof lacks, needed to walk a real train():
# Adam's _cuda_graph_capture_health_check() probes stream capture.
torch.cuda.is_current_stream_capturing = lambda *a, **k: False
try:
import torch.cuda.graphs as _cg # noqa: E402
_cg._cuda_isCurrentStreamCapturing = lambda *a, **k: False
except Exception:
pass
# A broken libmlx.so in the shared site-packages crashes transformers' Mac-only
# is_mlx_array probe on Linux; disable it.
try:
import transformers.utils.generic as _g # noqa: E402
_g._is_mlx_available = False
except Exception:
pass
# Dense (non-MoE) tiny model on purpose: MoE models route through Unsloth's
# grouped_gemm Triton kernel, which is CUDA-only and cannot run on a CPU runner.
_MODEL = "hf-internal-testing/tiny-random-LlamaForCausalLM"
def _load_plain():
"""Tiny plain HF model + tokenizer on CPU. Skips (not fails) if the model
cannot be fetched -- that is a network/hub issue, not an unsloth regression."""
from transformers import AutoModelForCausalLM, AutoTokenizer
try:
tok = AutoTokenizer.from_pretrained(_MODEL)
model = AutoModelForCausalLM.from_pretrained(_MODEL, dtype = torch.float32)
except OSError as e: # hub unreachable / model missing
pytest.skip(f"could not fetch {_MODEL} (network/hub): {str(e)[:150]}")
if tok.pad_token is None:
tok.pad_token = tok.eos_token
# Unsloth's GRPO path calls model.for_training()/for_inference() (added by
# FastLanguageModel). A plain HF model lacks them; supply minimal train/eval
# equivalents so the loop proceeds without the optimized wrapper.
if not hasattr(model, "for_training"):
model.for_training = lambda *a, **k: model.train()
if not hasattr(model, "for_inference"):
model.for_inference = lambda *a, **k: model.eval()
return model.to("cpu"), tok
@pytest.fixture(autouse = True)
def _require_stack():
global torch # the `import torch._dynamo` below would otherwise shadow it as local
if importlib.util.find_spec("unsloth") is None or importlib.util.find_spec("trl") is None:
pytest.skip("unsloth or trl not installed")
# A real import failure is a regression we want to surface, so do not guard it.
import unsloth # noqa: F401 -- patches TRL trainers to the Unsloth variants
# `import unsloth` reinstalls the real torch.compile (overwriting the eager
# passthrough set at module load), so the GRPO hot path (chunked_selective_
# log_softmax) would really compile -- and inductor picks the spoofed CUDA
# device, crashing on device props (`gcnArchName`). Re-apply the eager
# passthrough and flip dynamo's call-time kill switch so every @torch.compile
# runs eager regardless of when it was decorated. CPU eager is what we want.
torch.compile = _eager_compile
try:
import torch._dynamo # noqa: E402
torch._dynamo.config.disable = True
except Exception:
pass
def test_sft_trains_on_cpu(tmp_path):
from datasets import Dataset
from trl import SFTConfig, SFTTrainer
assert SFTTrainer.__name__ == "UnslothSFTTrainer", "SFT patch did not apply"
model, tok = _load_plain()
ds = Dataset.from_list([{"text": "The quick brown fox jumps over the lazy dog."}] * 8)
cfg = SFTConfig(
output_dir = str(tmp_path / "ci_sft"),
per_device_train_batch_size = 2,
max_steps = 2,
logging_steps = 1,
report_to = "none",
save_strategy = "no",
use_cpu = True,
max_length = None,
padding_free = False,
dataset_text_field = "text",
fp16 = False,
bf16 = False,
optim = "adamw_torch",
)
SFTTrainer(model = model, processing_class = tok, args = cfg, train_dataset = ds).train()
def test_grpo_trains_on_cpu(tmp_path):
from datasets import Dataset
from trl import GRPOConfig, GRPOTrainer
assert GRPOTrainer.__name__ == "UnslothGRPOTrainer", "GRPO patch did not apply"
model, tok = _load_plain()
ds = Dataset.from_list([{"prompt": "hi there"}] * 4)
cfg = GRPOConfig(
output_dir = str(tmp_path / "ci_grpo"),
per_device_train_batch_size = 2,
num_generations = 2,
max_steps = 2,
max_completion_length = 8,
logging_steps = 1,
report_to = "none",
temperature = 1.0,
beta = 0.0,
save_strategy = "no",
use_cpu = True,
use_vllm = False,
fp16 = False,
bf16 = False,
optim = "adamw_torch",
)
GRPOTrainer(
model = model,
processing_class = tok,
reward_funcs = [lambda completions, **k: [float(len(c)) for c in completions]],
args = cfg,
train_dataset = ds,
).train()
def test_dpo_trains_on_cpu(tmp_path):
from datasets import Dataset
from trl import DPOConfig, DPOTrainer
assert DPOTrainer.__name__ == "UnslothDPOTrainer", "DPO patch did not apply"
model, tok = _load_plain()
ds = Dataset.from_list(
[{"prompt": "Hi", "chosen": " hello friend", "rejected": " go away"}] * 8
)
cfg = DPOConfig(
output_dir = str(tmp_path / "ci_dpo"),
per_device_train_batch_size = 2,
max_steps = 2,
logging_steps = 1,
report_to = "none",
save_strategy = "no",
use_cpu = True,
beta = 0.1,
fp16 = False,
bf16 = False,
optim = "adamw_torch",
)
DPOTrainer(model = model, processing_class = tok, args = cfg, train_dataset = ds).train()