linux-kernel - Re: WARNING: at arch/x86/kernel/smp.c:119 native_smp_send

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Message-ID: <20120210210423.GJ5650@redhat.com>
Date:	Fri, 10 Feb 2012 16:04:23 -0500
From:	Don Zickus <dzickus@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Sasha Levin <levinsasha928@...il.com>,
	Josh Boyer <jwboyer@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Avi Kivity <avi@...hat.com>, kvm <kvm@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	x86 <x86@...nel.org>,
	Suresh B Siddha <suresh.b.siddha@...el.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: WARNING: at arch/x86/kernel/smp.c:119
 native_smp_send_reschedule+0x25/0x43()

On Fri, Feb 10, 2012 at 09:36:03PM +0100, Peter Zijlstra wrote:
> On Fri, 2012-02-10 at 15:31 -0500, Don Zickus wrote:
> > So my second patch which I will eventually post will just skip the WARN_ON
> > if the system is going down.  Not sure if that is the proper way to address
> > this problem or change all of the stop_this_cpu code to use a different
> > bitmask than the cpu_online bitmask (but then you run the risk of a stuck
> > IPI I guess if the cpu is halted without notifying anyone). 
> 
> Yeah, the async hard kill of all cpus is bound to make problems.. what
> I'm wondering is, why is this in the normal shutdown path and not
> specific to a hard panic?

I didn't write the original code, I just changed it from REBOOT_IRQ to
NMI and left all the stop_this_cpu stuff alone.

> 
> Trying to make this work is just not going to be pretty, and in the
> panic case we really don't care much.

Sure.

Cheers,
Don
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