From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Subject: Re: [PATCH] Update sched_domains_numa_masks when new cpus are onlined.
Date: Mon, 24 Sep 2012 15:27:09 +0530
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>, linux-kernel@vger.kernel.org, x86@kernel.org, linux-numa@vger.kernel.org, wency@cn.fujitsu.com, mingo@kernel.org, Thomas Gleixner <tglx@linutronix.de>

On 09/24/2012 03:08 PM, Peter Zijlstra wrote:  
>> +       hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
>>         hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
>>         hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
> 
> OK, so you really want your notifier to run before cpuset_cpu_active
> because otherwise you get that crash, yet you fail with the whole order
> thing.. You should not _ever_ rely on registration order.
> 

IMHO he isn't relying on registration order.. He uses the CPU_PRI_SCHED_ACTIVE
priority to ensure that the ordering of callbacks is right, isn't it?

Regards,
Srivatsa S. Bhat