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Date: Mon, 24 Sep 2012 20:19:27 +0200
From: Borislav Petkov <bp@amd64.org>
To: Conny Seidel <conny.seidel@amd.com>
Cc: Jan Kara <jack@suse.cz>, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Fengguang Wu <fengguang.wu@intel.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <jweiner@redhat.com>
Subject: Re: divide error: bdi_dirty_limit+0x5a/0x9e
Message-ID: <20120924181927.GA25762@aftab.osrc.amd.com>
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On Mon, Sep 24, 2012 at 08:16:50PM +0200, Conny Seidel wrote:
> Hi,
> 
> On Mon, 24 Sep 2012 16:36:09 +0200
> Borislav Petkov <bp@amd64.org> wrote:
> >[ … ]
> >
> >Conny, would you test pls?
> 
> Sure thing.
> Out of ~25 runs I only triggered it once, without the patch the
> trigger-rate is higher.
> 
> [   55.098249] Broke affinity for irq 81
> [   55.105108] smpboot: CPU 1 is now offline
> [   55.311216] smpboot: Booting Node 0 Processor 1 APIC 0x11
> [   55.333022] LVT offset 0 assigned for vector 0x400
> [   55.545877] smpboot: CPU 2 is now offline
> [   55.753050] smpboot: Booting Node 0 Processor 2 APIC 0x12
> [   55.775582] LVT offset 0 assigned for vector 0x400
> [   55.986747] smpboot: CPU 3 is now offline
> [   56.193839] smpboot: Booting Node 0 Processor 3 APIC 0x13
> [   56.212643] LVT offset 0 assigned for vector 0x400
> [   56.423201] Got negative events: -25

I see it:

__percpu_counter_sum does for_each_online_cpu without doing
get/put_online_cpus().

-- 
Regards/Gruss,
Boris.

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