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Date: Tue, 18 Aug 2009 18:35:32 +0800
From: Amerigo Wang <amwang@redhat.com>
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To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: "Eric W. Biederman" <ebiederm@xmission.com>, linux-kernel@vger.kernel.org,
       tony.luck@intel.com, linux-ia64@vger.kernel.org, linux-mm@kvack.org,
       Neil Horman <nhorman@redhat.com>, Andi Kleen <andi@firstfloor.org>,
       akpm@linux-foundation.org, bernhard.walle@gmx.de,
       Fenghua Yu <fenghua.yu@intel.com>, Ingo Molnar <mingo@elte.hu>,
       Anton Vorontsov <avorontsov@ru.mvista.com>
Subject: Re: [Patch 8/8] kexec: allow to shrink reserved memory
References: <20090812081731.5757.25254.sendpatchset@localhost.localdomain>	<20090812081906.5757.39417.sendpatchset@localhost.localdomain>	<m1bpmk8l1g.fsf@fess.ebiederm.org>	<4A83893D.50707@redhat.com>	<m1eirg5j9i.fsf@fess.ebiederm.org>	<4A83CD84.8040609@redhat.com>	<m1tz0avy4h.fsf@fess.ebiederm.org>	<4A8927DD.6060209@redhat.com>	<20090818092939.2efbe158.kamezawa.hiroyu@jp.fujitsu.com>	<4A8A4ABB.70003@redhat.com> <20090818172552.779d0768.kamezawa.hiroyu@jp.fujitsu.com>
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KAMEZAWA Hiroyuki wrote:
> On Tue, 18 Aug 2009 14:31:23 +0800
> Amerigo Wang <amwang@redhat.com> wrote:
>   
>>>     It's hidden from the system before mem_init() ?
>>>   
>>>       
>> Not sure, but probably yes. It is reserved in setup_arch() which is 
>> before mm_init() which calls mem_init().
>>
>> Do you have any advice to free that reserved memory after boot? :)
>>
>>     
>
> Let's see arch/x86/mm/init.c::free_initmem()
>
> Maybe it's all you want.
>
> 	- ClearPageReserved()
> 	- init_page_count()
> 	- free_page()
> 	- totalram_pages++
>   

Just FYI: calling ClearPageReserved() caused an oops: "Unable to handle 
paging request".

I am trying to figure out why...