Re: [PATCH] sched/proxy: allow SCHED_PROXY_EXEC with PREEMPT_RT

[Sebastian Andrzej Siewior]

On 2026-09-21 18:51:44 [+0800], Quchaosheng wrote:
> On 2026-09-21 12:09:21 [+0200], Sebastian Andrzej Siewior wrote:
> > Why exactly is this a good thing to do?
> 
> What the patch does is make a combination that the Kconfig itself already
> documents as broken ("Avoid some build failures w/ PREEMPT_RT until it can
> be fixed") compile again, and drop the RT stub in include/linux/sched.h
> whose parameter type did not match any caller. That is the whole of it.

Is there a build failure as of today or not?
The whole proxy exec thingy depends on !PREEMPT_RT, so there should be
no build failures.

> If that is not worth carrying, I would rather withdraw the patch than
> argue for it. Enabling a config that silently does nothing is a fair
> objection, and teaching the RT mutex to maintain blocked_on is the real
> work here.

I still fail to understand why we want it. It does nothing. The option
itself is document and once enabled CONFIG_SCHED_PROXY_EXEC does
something an !PREEMPT_RT and leads to a different behaviour if disabled.
But with your patch and PREEMPT_RT enabled there would be nothing that
CONFIG_SCHED_PROXY_EXEC does, would there be?

Sebastian