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Date: Wed, 28 Jul 2021 19:45:46 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: bof@bof.de
Cc: stable@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: stable 5.4.135 REGRESSION / once-a-day WARNING: at
 kthread_is_per_cpu+0x1c/0x20
Message-ID: <YQGXyiMb1IntqacG@kroah.com>
References: <61018d93.xsvXcO161PFLQFCX%bof@bof.de>
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In-Reply-To: <61018d93.xsvXcO161PFLQFCX%bof@bof.de>

On Wed, Jul 28, 2021 at 07:02:11PM +0200, bof@bof.de wrote:
> Hi,
> 
> first regression report in a long while... hope I'm doing this right.
> 
> I run self-build, from time to time, mainline kernels, in production, both on HP DL hosts + inside kvm VMs on these. I usually stick to a certain
> long term stable line for a year or three. As such, for a bit longer already, I'm running 5.4, starting somewhere at 5.4.4x. At the moment, I started
> to roll out 5.4.135 on a few of the hosts, and encounter a rare "WARNING: CPU ... PID ... at kthread_is_per_cpu+0x1c/0x20" splat (see full dmesg below)
> 
> Previous kernel I was running there, never seeing that, was 5.4.114
> 
> Searching a bit, turns up this 5.4.118 commit / backport:
> 	https://lore.kernel.org/stable/162074016514831@kroah.com/
> 	https://lore.kernel.org/lkml/20210407220628.3798191-2-valentin.schneider@arm.com/
> pointing to exactly the place shown in the dmesg trace.

Can you narrow this down to a specific commit using 'git bisect'?

thanks,

greg k-h