linux-kernel - Re: [BUG REPORT] x86/apic: CPU Hang in x86 VM During Kdump

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Message-ID: <4426d19d-7f7e-411b-8573-36b8990e5d9a@huawei.com>
Date: Tue, 29 Jul 2025 21:35:29 +0800
From: Yipeng Zou <zouyipeng@...wei.com>
To: Thomas Gleixner <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
	<peterz@...radead.org>, <sohil.mehta@...el.com>, <rui.zhang@...el.com>,
	<arnd@...db.de>, <yuntao.wang@...ux.dev>, <linux-kernel@...r.kernel.org>
Subject: Re: [BUG REPORT] x86/apic: CPU Hang in x86 VM During Kdump


在 2025/7/29 16:53, Thomas Gleixner 写道:
> On Sun, Jul 27 2025 at 22:01, Thomas Gleixner wrote:
>
> But looking even deeper. machine_crash_shutdown() does not end up in
> stop_other_cpus() at all. It immediately uses the NMI shutdown. There
> are still a few inconsistencies in that code, but they are not really
> critical.
>
> So the actual scenario is:
>
> CPU0			  CPU2
> ========================  ======================
> reboot			  Panic
> machine shutdown	  Kdump
> 			  machine_crash_shutdown()
> stop other cpus
> send_IPIs(REBOOT)	  --> REBOOT vector becomes pending in IRR
> wait timeout
>                            send NMI stop
> NMI -> CPU stop
>                            jump to crash kernel
>
> So the patch I gave you should handle the reboot vector pending in IRR
> gracefully. Can you please give it a try?

Hi Thomas:

     Thanks for your time!

     Indeed, It invokes kdump_nmi_shootdown_cpus() and uses the NMI 
shutdown.

     I started the test run today, but this is a low-probability to hit 
this path, might take a while.

-- 
Regards,
Yipeng Zou