From: Nick Piggin <npiggin@suse.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Alexey Zaytsev <alexey.zaytsev@gmail.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Laurent Riffard <laurent.riffard@free.fr>,
Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: next-20090107: WARNING: at kernel/sched.c:4435 sub_preempt_count
Date: Wed, 14 Jan 2009 03:00:40 +0100 [thread overview]
Message-ID: <20090114020040.GA19806@wotan.suse.de> (raw)
In-Reply-To: <20090111024945.GC7077@elte.hu>
On Sun, Jan 11, 2009 at 03:49:45AM +0100, Ingo Molnar wrote:
>
> * Alexey Zaytsev <alexey.zaytsev@gmail.com> wrote:
>
> > One more instance of http://marc.info/?l=linux-kernel&m=123134586202636&w=2
> > Added Ingo Molnar to CC.
>
> added Nick on Cc:. Nick, it's about:
>
> > commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd
> > Author: Nick Piggin <nickpiggin@yahoo.com.au>
> > Date: Tue Sep 30 20:50:27 2008 +1000
> >
> > sched: improve preempt debugging
>
> causing a seemingly spurious warning.
I don't know how it is spurious... Presumably the sequence _would_ have
caused preempt count to go negative if the bkl were not held...
__do_softirq does a __local_bh_disable on entry, and it seems like the
_local_bh_enable on exit is what causes this warning. So something is
unbalanced somehow. Or is it some weird thing we do in early boot that
I am missing?
Can you put in some printks around these functions in early boot to
get an idea of what preempt_count is doing?
next prev parent reply other threads:[~2009-01-14 2:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-08 23:17 Laurent Riffard
2009-01-09 10:09 ` Alexey Zaytsev
2009-01-11 2:49 ` Ingo Molnar
2009-01-14 2:00 ` Nick Piggin [this message]
2009-01-18 18:22 ` Alexey Zaytsev
2009-01-18 18:24 ` Ingo Molnar
2009-01-18 18:24 ` Alexey Zaytsev
2009-01-25 0:33 ` Alexey Zaytsev
2009-01-26 14:43 ` Ingo Molnar
2009-01-26 14:53 ` Alexey Zaytsev
2009-01-26 15:09 ` Ingo Molnar
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