Re: [PATCH] x86/apic: Fix circular locking dependency between console and hrtimer locks
From: Leon Romanovsky
Date: Mon Apr 27 2020 - 11:54:15 EST
On Mon, Apr 27, 2020 at 05:31:21PM +0200, Thomas Gleixner wrote:
> Leon Romanovsky <leon@xxxxxxxxxx> writes:
> > OK, I consulted with verification people and back then the trigger was:
> > Reproduce when run "echo 1 > /sys/kernel/debug/clear_warn_once" after
> > reboot
>
> That explains it.
>
> > [ 0.937310] Freeing SMP alternatives memory: 32K
> > [ 0.940471] TSC deadline timer enabled
>
> So here is the first one which sets 'once'. Of course if you clear 'once'
> afterwards then this triggers because the context is completely
> different.
>
> So the right thing to do is to move this out of __setup_APIC_LVTT() and
> be done with it.
Thanks a lot.