Re: [QUESTION] Are these issues PREEMPT_RT-specific?

[Steven Rostedt]

On Fri, 4 Sep 2026 16:11:41 +0800
Ran Hongyun <ranhongyun1@xxxxxxxxxx> wrote:

> 1.Priority inversion – On PREEMPT_RT, rwlock_t readers lack priority
> inheritance (PI), so a low-priority reader holding the lock can be
> preempted by a medium-priority task, blocking a high-priority writer
> indefinitely.

Priority inheritance to boost readers from a writer is an exponentially
difficult problem to solve. PI is already hard enough, but multiple readers
is exponentially more difficult (we tried).

The solution is to make sure you do not have any RT critical tasks taking
rw writer locks. This is something that the Runtime Verifier (RV) can help
make sure you never hit this situation.

-- Steve