Re: [PATCH v3 0/4] kcov, usb: Fix invalid context sleep in softirq path on PREEMPT_RT

On Sun, 3 Aug 2025 07:20:41 +0000 Yunseong Kim ysk@kzalloc.com wrote:

This patch series resolves a sleeping function called from invalid context bug that occurs when fuzzing USB with syzkaller on a PREEMPT_RT kernel.

The regression was introduced by the interaction of two separate patches: one that made kcov's internal locks sleep on PREEMPT_RT for better latency

Just so I fully understand this change. It is basically reverting the "better latency" changes? That is, with KCOV anyone running with PREEMPT_RT can expect non deterministic latency behavior?

This should be fully documented. I assume this will not be a problem as kcov is more for debugging and should not be enabled in production.

-- Steve