linux-kernel - Re: [PATCH] sched_ext: Fix possible deadlock in the deferred_irq

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Message-ID: <001184f0619f11ba3dc767e237ba99a5@kernel.org>
Date: Thu, 13 Nov 2025 08:32:23 -1000
From: Tejun Heo <tj@...nel.org>
To: Zqiang <qiang.zhang@...ux.dev>
Cc: void@...ifault.com, arighi@...dia.com, changwoo@...lia.com, sched-ext@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched_ext: Fix possible deadlock in the deferred_irq_workfn()

On Thu, Nov 13, 2025 at 07:43:55PM +0800, Zqiang wrote:
> For PREEMPT_RT=y kernels, the deferred_irq_workfn() is executed in
> the per-cpu irq_work/* task context and not disable-irq, if the rq
> returned by container_of() is current CPU's rq, the following scenarios
> may occur:
>
> lock(&rq->__lock);
> <Interrupt>
>   lock(&rq->__lock);
>
> This commit use IRQ_WORK_INIT_HARD() to replace init_irq_work() to
> initialize rq->scx.deferred_irq_work, make the deferred_irq_workfn()
> is always invoked in hard-irq context.
>
> Signed-off-by: Zqiang <qiang.zhang@...ux.dev>

Applied to sched_ext/for-6.18-fixes.

Thanks.

--
tejun