linux-kernel - Re: [PATCH v2 06/31] arm64: MMU fault handling and page table management

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Message-Id: <201208151347.01169.arnd@arndb.de>
Date:	Wed, 15 Aug 2012 13:47:00 +0000
From:	Arnd Bergmann <arnd@...db.de>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v2 06/31] arm64: MMU fault handling and page table management

On Tuesday 14 August 2012, Catalin Marinas wrote:
> +
> +pgd_t *pgd_alloc(struct mm_struct *mm)
> +{
> +	pgd_t *new_pgd;
> +
> +	new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, PGD_ORDER);
> +	if (!new_pgd)
> +		return NULL;
> +
> +	memset(new_pgd, 0, PAGE_SIZE << PGD_ORDER);
> +
> +	return new_pgd;
> +}
> +
> +void pgd_free(struct mm_struct *mm, pgd_t *pgd)
> +{
> +	free_pages((unsigned long)pgd, PGD_ORDER);
> +}
 
According to the documentation, you should only need 8kb for the pgd on
a 64kb page system. Is it required that you use up a full page here?

	Arnd
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