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Date: Fri, 3 Apr 2026 23:08:04 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: John Stultz <jstultz@google.com>, LKML <linux-kernel@vger.kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Qais Yousef <qyousef@layalina.io>, Ingo Molnar <mingo@redhat.com>,
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	Valentin Schneider <vschneid@redhat.com>,
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	Zimuzo Ezeozue <zezeozue@google.com>, Mel Gorman <mgorman@suse.de>,
	Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
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	kuyo chang <kuyo.chang@mediatek.com>, hupu <hupu.gm@gmail.com>,
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Subject: Re: [PATCH v26 00/10] Simple Donor Migration for Proxy Execution
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In-Reply-To: <0f5b0dd9-ef6e-462b-ac89-6f37c4261241@amd.com>

On Fri, Apr 03, 2026 at 09:09:31PM +0530, K Prateek Nayak wrote:

> > +	/*
> > +	 * We're being taken off the runqueue, cannot still be blocked_on
> > +	 * anything. This also means that delay_dequeue can not have
> > +	 * blocked_on.
> > +	 */
> > +	clear_task_blocked_on(p, NULL);
> > +	
> 
> Oh! I remember why we couldn't do this - if we clear the
> "blocked_on" via proxy_deactivate(), we might be delayed on
> the owner's CPU *outside* of the task's affinity.
> 
> In that case, we don't want to re-enqueue it there since it'll
> violate affinity and the "blocked_on" relation forces it down
> the sched_proxy_exec() path in ttwu_runnable() which will fix
> it via a full wakeup.

Ah indeed.