linux-kernel - RE: [PATCH] smpboot: Add NULL check before kthread

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Message-ID: <LV3PR11MB8768DB939A646E82EDDE0D4CF5A0A@LV3PR11MB8768.namprd11.prod.outlook.com>
Date: Wed, 10 Dec 2025 08:21:45 +0000
From: "Kumar, Kaushlendra" <kaushlendra.kumar@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>, "peterz@...radead.org"
	<peterz@...radead.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] smpboot: Add NULL check before kthread_unpark()

On Mon, Nov 24 2025, Thomas Gleixner wrote:
> On Mon, Nov 24 2025 at 10:41, Kaushlendra Kumar wrote:
>> Add NULL check for tsk before calling kthread_unpark() in
>> smpboot_unpark_thread() to prevent potential null pointer dereference.
>
> How is that ever going to be NULL?
Thanks for the review.
Here I was only concerned about edge cases during CPU hotplug state transitions.

Could you help clarify: are there any scenarios during the CPU hotplug state 
transition where this function might be called without a valid task, or is the 
current flow guaranteed to always have tsk initialized at this point?

If the existing code ensure tsk is always valid here, will drop this patch.



-Kaushlendra