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The logic there is already subtle and I want to avoid adding > > misleading checks. > > Thought a bit more about it and the only thing that can change are the > running state and migration disabled, right? So, maybe just test those again > after the lock switch? Right, without proxy execution, the DSQ lock and holding_cpu handshake guarantee that with an unchanged holding_cpu the task could not have been dequeued or started running during the rq-lock handoff. Proxy execution is the exception: a task can start physically executing as a lock owner while its own scheduling context remains on the DSQ, allowing its on-CPU or migration-disabled state to change without clearing holding_cpu. I'll leave the existing validation unchanged and, only when proxy execution is enabled, recheck the running and migration-disabled state after switching to the source rq lock. Thanks for taking a look! -Andrea