Re: [PATCHSET v14 sched_ext/for-7.4] sched: Make proxy execution compatible with sched_ext

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Sep 24, 2026 at 01:40:27PM +0530, K Prateek Nayak wrote:
> On 9/24/2026 1:29 PM, Peter Zijlstra wrote:
> >>   Almost like switching_to_scx(), except it needs to change ctx->queued in case
> >>   of p->is_blocked. Hence a new callback ran before sched_change_begin().
> > 
> > And I wonder, would something like so work?
> > 
> > ---
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index adcc9264c0c6..3e7691d24930 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -11215,8 +11215,13 @@ void sched_change_end(struct sched_change_ctx *ctx)
> >  	 */
> >  	WARN_ON_ONCE(p->sched_class != ctx->class && !(ctx->flags & ENQUEUE_CLASS));
> >  
> > -	if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to)
> > -		p->sched_class->switching_to(rq, p);
> > +	if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to) {
> > +		bool block = p->sched_class->switching_to(rq, p);
> > +		if (block && p->is_blocked) {
> 
> Shouldn't this also check for "ctx->queued"?
> 
> > +			block_task(rq, p, READ_ONCE(p->__state));
> 
> Otherwise we may block an already off rq task.
> 
> > +			ctx->queued = false;
> > +		}
> > +	}

Yes.