linux-kernel - Re: [PATCH sched_ext/for-6.18-fixes] sched_ext: Fix scx_kick_pseqs corruption on concurrent scheduler loads

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Message-ID: <aO6yrTkjUqMrq3cH@slm.duckdns.org>
Date: Tue, 14 Oct 2025 10:29:33 -1000
From: Tejun Heo <tj@...nel.org>
To: Andrea Righi <arighi@...dia.com>
Cc: David Vernet <void@...ifault.com>, Changwoo Min <changwoo@...lia.com>,
	Phil Auld <pauld@...hat.com>,
	Emil Tsalapatis <emil@...alapatis.com>, sched-ext@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH sched_ext/for-6.18-fixes] sched_ext: Fix scx_kick_pseqs
 corruption on concurrent scheduler loads

On Mon, Oct 13, 2025 at 10:36:34PM +0200, Andrea Righi wrote:
> If we load a BPF scheduler while another scheduler is already running,
> alloc_kick_pseqs() would be called again, overwriting the previously
> allocated arrays.
> 
> Fix by moving the alloc_kick_pseqs() call after the scx_enable_state()
> check, ensuring that the arrays are only allocated when a scheduler can
> actually be loaded.
> 
> Fixes: 14c1da3895a11 ("sched_ext: Allocate scx_kick_cpus_pnt_seqs lazily using kvzalloc()")
> Signed-off-by: Andrea Righi <arighi@...dia.com>

Applied to sched_ext/for-6.18-fixes.

Thanks.

-- 
tejun