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Date:   Mon, 8 Nov 2021 09:12:00 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Colin King (gmail)" <colin.i.king@googlemail.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: DEAD callback error for CPU, WARNING: CPU: 3 PID: 1134 at
 kernel/cpu.c:1163 _cpu_down+0x20a/0x3a0
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References: <f6a0f4be-ad53-489c-0036-09dead99f368@gmail.com>
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On Sun, Nov 07, 2021 at 11:59:17AM +0000, Colin King (gmail) wrote:
> On a SMP system in a VM, a deadlock callback error can be reproduced with
> 5.15, tested from head at commit d4439a1189f93d0ac1eaf0197db8e6b3e197d5c7
> 
> Didn't see this issue on 5.13
> 
> How to reproduce:
> 
> git clone https://github.com/ColinIanKing/stress-ng
> cd stress-ng
> make -j $(nproc)
> sudo ./stress-ng --cpu-online 0 -t 15 --pathological
> 
> Tested on a 8 thread virtual machine, 4MB of memory.
> 
> [ 2239.378724] smpboot: CPU 6 is now offline
> [ 2239.379443] smpboot: Booting Node 0 Processor 6 APIC 0x6
> [ 2239.380169] kvm-clock: cpu 6, msr 79201181, secondary cpu clock
> [ 2239.401652] ------------[ cut here ]------------
> [ 2239.401658] DEAD callback error for CPU6
> [ 2239.401721] WARNING: CPU: 3 PID: 1134 at kernel/cpu.c:1163
> _cpu_down+0x20a/0x3a0

Can you do the same with whatever magic is required to get the
pr_debug() output from cpuhp_down_callbacks() included?