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Date: Wed, 4 Mar 2009 23:12:40 +0900
From: Akinobu Mita <akinobu.mita@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
       linux-mm@kvack.org, akpm@linux-foundation.org
Subject: Re: [PATCH] generic debug pagealloc
Message-ID: <20090304141238.GA7168@localhost.localdomain>
References: <20090303160103.GB5812@localhost.localdomain> <20090303160503.GA6538@elte.hu>
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On Tue, Mar 03, 2009 at 05:05:03PM +0100, Ingo Molnar wrote:
> if every architecture supports it now then i guess this config 
> switch can go away:
> 
> > +config ARCH_SUPPORTS_DEBUG_PAGEALLOC
> > +	def_bool y

The generic debug pagealloc needs the poison flag for each struct page.

So I introduced CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC for x86, powerpc,
sparc (64bit), and s390. If there is no CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC,
make config prompts the generic debug pagealloc in mm/Kconfig.debug for the
other architectures.

I was trying to add cleaner config dependency but
CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC is my solution for now.