linux-kernel - Re: [PATCH] sched_ext: Fix NULL pointer deref and warnings during scx teardown

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Message-ID: <aYOnW5z72oduefZx@slm.duckdns.org>
Date: Wed, 4 Feb 2026 10:08:59 -1000
From: Tejun Heo <tj@...nel.org>
To: Andrea Righi <arighi@...dia.com>
Cc: David Vernet <void@...ifault.com>, Changwoo Min <changwoo@...lia.com>,
	Emil Tsalapatis <emil@...alapatis.com>, sched-ext@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched_ext: Fix NULL pointer deref and warnings during
 scx teardown

On Tue, Feb 03, 2026 at 03:01:30PM +0100, Andrea Righi wrote:
> > Nope, I can still trigger this (with the same modified scx_simple +
> > stress-ng --race-sched 0:
> 
> A quick reproducer:
> https://github.com/sched-ext/scx/tree/scx-bug
> 
>  $ make
>  $ vng -vr -- "stress-ng --race-sched 0 & ./build/scheds/c/scx_bug"
>  ...
>  [    3.375119] BUG: kernel NULL pointer dereference, address: 00000000000001c0
>  [    3.375836] RIP: 0010:set_cpus_allowed_scx+0x1a/0xa0
> 
> It happens almost immediately.

This should fix it:

  http://lkml.kernel.org/r/fc034891cef55029c16122f4279e4057@kernel.org

Thanks.

-- 
tejun