linux-kernel - Re: [PATCH] sched/fair: Add null pointer check to pick_next

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Message-ID: <20250324115613.GD14944@noisy.programming.kicks-ass.net>
Date: Mon, 24 Mar 2025 12:56:13 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Pat Cody <pat@...cody.io>
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,
	riel@...riel.com, patcody@...a.com, kernel-team@...a.com,
	stable@...r.kernel.org
Subject: Re: [PATCH] sched/fair: Add null pointer check to pick_next_entity()

On Thu, Mar 20, 2025 at 01:53:10PM -0700, Pat Cody wrote:
> pick_eevdf() can return null, resulting in a null pointer dereference
> crash in pick_next_entity()

If it returns NULL while nr_queued, something is really badly wrong.

Your check will hide this badness.

Does something like:

  https://lkml.kernel.org/r/20250128143949.GD7145@noisy.programming.kicks-ass.net

help?