[CI][BugFix][AMD] Add check for model_config being None and update conftest.py to load AITER of available to fix Kernels MoE Test % N

[rasmith]

Purpose

This PR broke many tests (over 30) and this PR fixed one test in the Kernels MoE Test %N group, but when the test is run as a group using

pytest -sv kernels/moe

the first test that run does not load AITER ops and when subsequent tests run, they will also not have AITER ops loaded.

This PR loads the ops in vllm._aiter_ops but then ensures that VLLM_ROCM_USE_AITER=0 when tests run. This ensures that tests that need the function pointers in vllm._aiter_ops are available, but for tests that do not want to use AITER and may depend on VLLM_ROCM_USE_AITER=0 will run properly.

In the context of testing, it does seem reasonable to load AITER ops on ROCm if AITER is available. So, I added a function to conftest.py to load AITER ops if they are available, which now lets the entire group pass.

This PR introduced a check in vllm.py that crashes if the VllmConfig model_config is None, so I added a check to see if the model_config is not None to prevent this from happening.

Test Plan

pytest -sv kernels/moe

Test Result

1950 passed, 5399 skipped, 8 warnings

---

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[gemini-code-assist]

Code Review

This pull request introduces two important fixes. First, it resolves a potential AttributeError in vllm/config/vllm.py by adding a necessary null check for cfg.model_config before accessing its attributes. This is a good defensive programming practice that prevents crashes. Second, it addresses a CI failure for MoE tests on ROCm by centralizing the AITER op loading logic into tests/conftest.py. This ensures that the test environment is set up correctly for all tests in the suite, improving the reliability of the CI pipeline. The corresponding cleanup in test_rocm_aiter_topk.py is also appropriate. The changes are well-implemented and clearly explained. Overall, this is a solid contribution that improves both code robustness and test stability.

[robertgshaw2-redhat]

hm, not sure if this is a good idea. I think many tests explicity set or dont set this env

[rasmith]

I updated it so that only the function pointers are loaded, which was happening before, but the environment variable is set to 0.

[rasmith]

@robertgshaw2-redhat I could also do this in _aiter_ops.py, which also works. Basically, the functions get loaded but the env var will be unset:

@@ -36,7 +36,7 @@ def is_aiter_found_and_supported() -> bool:
     Checks: platform (ROCm), device arch (gfx9), library existence,
     and VLLM_ROCM_USE_AITER env variable.
     """
-    if current_platform.is_rocm() and IS_AITER_FOUND and envs.VLLM_ROCM_USE_AITER:
+    if current_platform.is_rocm() and IS_AITER_FOUND:
         from vllm.platforms.rocm import on_gfx9

[tjtanaa]

@rasmith can you check if this PR #33749 resolves the issue that this PR is trying to address? We have worked out a way to resolve the log regression without complicating the imports.

[rasmith]

@rasmith can you check if this PR #33749 resolves the issue that this PR is trying to address? We have worked out a way to resolve the log regression without complicating the imports.

@tjtanaa Yes, it will cause vllm._aiter_ops functions to always get loaded if on ROCm and the aiter library is available, even if VLLM_ROCM_USE_AITER is 0, which is what should happen IMO.

Closing this PR and opening this one to fix the rest of the issues in the test group.