linux-kernel - Re: [PATCH] sched: Proxy yields to donor tasks

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Message-ID: <20251106105735.GO3245006@noisy.programming.kicks-ass.net>
Date: Thu, 6 Nov 2025 11:57:35 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Fernand Sieber <sieberf@...zon.com>
Cc: mingo@...hat.com, juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, linux-kernel@...r.kernel.org,
	dwmw@...zon.co.uk, jschoenh@...zon.de, liuyuxua@...zon.com
Subject: Re: [PATCH] sched: Proxy yields to donor tasks

On Thu, Nov 06, 2025 at 12:40:10PM +0200, Fernand Sieber wrote:
> When executing a task in proxy context, handle yields as if they were
> requested by the donor task.

I'll modify this to say it matches the traditional PI semantics.

> This avoids scenario like proxy task yielding, pick next task selecting the
> same previous blocked donor, running the proxy task again, etc.
> 
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Fernand Sieber <sieberf@...zon.com>

Thanks, I'll add:

Reported-by: kernel test robot <oliver.sang@...el.com>
Closes: https://lore.kernel.org/oe-lkp/202510211205.1e0f5223-lkp@intel.com

Also, for now proxy and ext are mutually exclusive, but yeah, might as
convert that one now too. At some point someone will have to go through
all that.