Re: [tip:timers/urgent] [timers/migration] 8cdb61838e: WARNING:at_kernel/time/timer_migration.c:#tmigr_connect_child_parent

[Anna-Maria Behnsen <anna-maria@linutronix.de>]

Hi Paul,

"Paul E. McKenney" <paulmck@kernel.org> writes:

> On Wed, Jul 10, 2024 at 04:37:00PM +0800, kernel test robot wrote:
>> 
>> 
>> Hello,
>> 
>> kernel test robot noticed "WARNING:at_kernel/time/timer_migration.c:#tmigr_connect_child_parent" on:
>> 
>> commit: 8cdb61838ee5c63556773ea2eed24deab6b15257 ("timers/migration: Move hierarchy setup into cpuhotplug prepare callback")
>> https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git timers/urgent
>
> For whatever it is worth, I am also seeing this on refscale runs on
> recent -next.
>
> The reproducer is to clone perfbook [1] in your ~/git directory
> (as in ~/git/perfboot), then run this from your Linux source tree,
> preferably on a system with few CPUs:
>
> bash ~/git/perfbook/CodeSamples/defer/rcuscale.sh
>
> The output will have "FAIL" in it, which indicates that the corresponding
> guest OS splatted.  If it would be useful, I would be happy to produce
> a one-liner that runs the guest OS only once and leaves the console
> output around.  Otherwise, I will continue being lazy.  ;-)

Thanks for the report. I found the root cause for it and I am working on
a fix as the commit which triggers the warning also has another
problem... And I already requested to drop the tip timers/urgent patches
(at least my patches).

So, enjoy being lazy!

Thanks,

	Anna-Maria