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Date: Mon, 3 Aug 2026 10:38:11 -1000
From: Tejun Heo <tj@kernel.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: David Vernet <void@manifault.com>, Changwoo Min <changwoo@igalia.com>,
	John Stultz <jstultz@google.com>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	Christian Loehle <christian.loehle@arm.com>,
	David Dai <david.dai@linux.dev>, Koba Ko <kobak@nvidia.com>,
	Aiqun Yu <aiqun.yu@oss.qualcomm.com>, Shuah Khan <shuah@kernel.org>,
	sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/15] sched_ext: Generalize the reject DSQ reenqueue path
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References: <20260728154425.1549660-1-arighi@nvidia.com>
 <20260728154425.1549660-10-arighi@nvidia.com>
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On Mon, Aug 03, 2026 at 10:35:16AM -1000, Tejun Heo wrote:
> On Tue, Jul 28, 2026 at 05:43:27PM +0200, Andrea Righi wrote:
> ...
> > +static void scx_reenq_reject(struct rq *rq)
> > +{
> > +	LIST_HEAD(tasks);
> > +	struct task_struct *p, *n;
> > +
> > +	lockdep_assert_rq_held(rq);
> > +
> > +	if (list_empty(&rq->scx.reject_dsq.list))
> > +		return;
> > +
> > +	/*
> > +	 * Move tasks to a private list so a task re-rejected by
> > +	 * scx_do_enqueue_task() below isn't revisited this round.
> > +	 */
> > +	list_for_each_entry_safe(p, n, &rq->scx.reject_dsq.list, scx.dsq_list.node) {
> > +		u32 reason = p->scx.reject_reason;
> > +
> > +		/* migration_pending tasks should have bypassed to local DSQ */
> > +		if (WARN_ON_ONCE(p->migration_pending))
> > +			continue;
> > +		if (WARN_ON_ONCE(!reason))
> > +			continue;
> > +
> > +		scx_dispatch_dequeue(rq, p);
> > +		p->scx.reject_reason = SCX_TASK_REENQ_NONE;
> > +
> > +		if (WARN_ON_ONCE(p->scx.flags & SCX_TASK_REENQ_REASON_MASK))
> > +			p->scx.flags &= ~SCX_TASK_REENQ_REASON_MASK;
> > +		p->scx.flags |= reason;
> 
> Can you separate out code movement and actual changes into separate patches?
> Even for relatively simple changes, combining move and changes adds
> significant unnecessary review friction.

I wonder whether the reason can be carried in p->scx.flags from the
rejection site instead of bouncing through p->scx.reject_reason.

Thanks.

-- 
tejun