linux-kernel - Re: BUG: using smp_processor_id() during suspend with 2.6.25-rc8

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Message-ID: <Pine.LNX.4.64.0804110122470.3896@jikos.suse.cz>
Date:	Fri, 11 Apr 2008 01:25:13 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Pavel Machek <pavel@....cz>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Andi Kleen <andi@...stfloor.org>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: BUG: using smp_processor_id() during suspend with 2.6.25-rc8

On Thu, 10 Apr 2008, Pavel Machek wrote:

> > > > sysdevs were always supposed to run completely with interrupts off. If they 
> > > > don't anymore that's some kind of higher level resume code bug which you need 
> > > > to fix there, not hack around in the low level code.
> > > They are executed with interrupts disabled, on one CPU.
> > So, any idea why mce_resume() -> mce_init() -> debug_smp_processor_id() 
> > triggers the warning? Apparently preempt_count is zero, irqs_disabled() 
> > returns false, and cpumask_of_cpu() is not equal to current->cpus_allowed.
> We are single-threaded because we 'unplugged' all the other cpus... but 
> I'm not sure the BUG() code realises that...

That's unrelated, right? The real problem here is that irqs_disabled() 
call inside debug_smp_processor_id() signalized that interrupts are 
enabled, and that (correctly) triggered the bug.

-- 
Jiri Kosina
SUSE Labs
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