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Date: Fri, 25 Feb 2011 11:03:36 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86,mm,64bit: Round up memory boundary for
 init_memory_mapping_high()
Message-ID: <20110225100336.GA26608@elte.hu>
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* Yinghai Lu <yinghai@kernel.org> wrote:

>  init_memory_mapping_active_regions(unsigned long start, unsigned long end)
>  {
>  	struct mapping_work_data data;
> +	int use_gbpages;
> +
> +	/* see init_memory_mapping() for the setting */
> +#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
> +	use_gbpages = 0;
> +#else
> +	use_gbpages = direct_gbpages;
> +#endif

Sigh. You should *never* ever even think about writing such code. It only results in 
crap, and in crap duplicated elsewhere as well:

if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
        /*
         * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
         * This will simplify cpa(), which otherwise needs to support splitting
         * large pages into small in interrupt context, etc.
         */
        use_pse = use_gbpages = 0;
#else
        use_pse = cpu_has_pse;
        use_gbpages = direct_gbpages;
#endif

Thanks,

	Ingo