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Date: Wed, 25 Mar 2026 16:55:04 +0100
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiayuan Chen <jiayuan.chen@linux.dev>, linux-rt-devel@lists.linux.dev,
	Clark Williams <clrkwllms@kernel.org>, linux-kernel@vger.kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH v1] irq_work: Fix use-after-free in irq_work_single on
 PREEMPT_RT
Message-ID: <20260325155504.tm4zHWMI@linutronix.de>
References: <20260325030508.321405-1-jiayuan.chen@linux.dev>
 <20260325111351.1d38a0bc@gandalf.local.home>
 <20260325153826.EbSqlX_n@linutronix.de>
 <20260325115315.052e34ac@gandalf.local.home>
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In-Reply-To: <20260325115315.052e34ac@gandalf.local.home>

On 2026-03-25 11:53:15 [-0400], Steven Rostedt wrote:
> On Wed, 25 Mar 2026 16:38:26 +0100
> Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> 
> > Most irq-work aren't free()ed since they are static and remain around.
> > There is no task assigned if there is no active waiter.
> > Wouldn't it be easier to kfree_rcu() the struct using the irq-work?
> 
> I guess we should add some kind of helper then. Like tracepoints have.
> 
>    tracepoint_synchronize_unregister()
> 
> Perhaps have a:
> 
>    irq_work_synchronize_free();
> 
> Or something like that to let developers know that they just can't safely free a
> structure that contains an irq_work?

That sounds great.

> -- Steve

Sebastian