[CI Failure] Fix OOM with test_oot_registration_embedding

[mgoin]

Purpose

FIX #20148

The models/test_oot_registration.py::test_oot_registration_embedding test seems to be failing in CI consistently with a context length OOM

https://buildkite.com/vllm/ci/builds/22737/steps/canvas?sid=0197acae-970a-43ee-9fef-108d8a58da0c#0197acae-98db-423d-8af9-eb4eb401f1b4/212-1320

[2025-06-26T16:27:15Z] ERROR 06-26 09:27:15 [core.py:519] ValueError: To serve at least one request with the models's max seq len (8192), (2.63 GiB KV cache is needed, which is larger than the available KV cache memory (1.64 GiB). Based on the available memory, the estimated maximum model length is 5088. Try increasing `gpu_memory_utilization` or decreasing `max_model_len` when initializing the engine.

Test Plan

Green CI for this test

Test Result

https://buildkite.com/vllm/fastcheck/builds/28504/steps/canvas?jid=0197ad94-571b-474d-9172-cb63c661f112

[github-actions]

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[gemini-code-assist]

Summary of Changes

Hello @mgoin, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request aims to resolve a recurring Out-Of-Memory (OOM) issue observed in CI for a specific embedding test. By constraining the maximum model length used within the test, it prevents excessive memory consumption, thereby improving the reliability and stability of the CI pipeline for this test case.

Highlights

• Test Stability: Addressed a consistent Out-Of-Memory (OOM) error in the test_oot_registration_embedding test by explicitly setting a reduced max_model_len during LLM initialization.

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[gemini-code-assist]

Code Review

The pull request addresses an out-of-memory (OOM) error in the test_oot_registration_embedding test by explicitly setting max_model_len to 2048. This is a direct and appropriate fix for the issue observed in CI, as it reduces the memory required for the KV cache. The change is localized to the failing test and appears correct. I have no further suggestions.