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Date: Fri, 11 Feb 2005 18:56:09 -0600
From: Nathan Lynch <ntl@pobox.com>
To: Matthias-Christian Ott <matthias.christian@tiscali.de>
Cc: lkml <linux-kernel@vger.kernel.org>, Rusty Russell <rusty@rustcorp.com.au>,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: 2.6-bk: cpu hotplug + preempt = smp_processor_id warnings galore
Message-ID: <20050212005609.GB14499@otto>
References: <20050211232821.GA14499@otto> <420D4646.4010600@tiscali.de>
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On Sat, Feb 12, 2005 at 12:56:54AM +0100, Matthias-Christian Ott wrote:
> Nathan Lynch wrote:
> 
> >With 2.6.11-rc3-bk7 on ppc64 I am seeing lots of smp_processor_id
> >warnings whenever I hotplug cpus:
...
>
> Use get_cpu() (It disables preemption) or __smp_processor_id () (on a smp).

It's not necessarily that simple (ok, maybe the idle loop warning is).
But at least one of the warnings I listed appears to be caused by a
kernel thread that is normally bound to a particular cpu trying to do
normal processing on another cpu before it has stopped.  Injudicious
use of __smp_processor_id or get_cpu in this case would only obscure
the problem.


Nathan