linux-kernel - Re: [PATCH v3 06/12] Add get_user_pages() variant that fails if major fault is required.

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Date:	Sun, 17 Jan 2010 10:43:43 -0500
From:	Christoph Hellwig <hch@...radead.org>
To:	Gleb Natapov <gleb@...hat.com>
Cc:	kvm@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, avi@...hat.com, mingo@...e.hu,
	a.p.zijlstra@...llo.nl, tglx@...utronix.de, hpa@...or.com,
	riel@...hat.com, cl@...ux-foundation.org
Subject: Re: [PATCH v3 06/12] Add get_user_pages() variant that fails if
	major fault is required.

On Tue, Jan 05, 2010 at 04:12:48PM +0200, Gleb Natapov wrote:
> This patch add get_user_pages() variant that only succeeds if getting
> a reference to a page doesn't require major fault.

>  
> +int get_user_pages_noio(struct task_struct *tsk, struct mm_struct *mm,
> +		unsigned long start, int nr_pages, int write, int force,
> +		struct page **pages, struct vm_area_struct **vmas)
> +{
> +	int flags = FOLL_TOUCH | FOLL_MINOR;
> +
> +	if (pages)
> +		flags |= FOLL_GET;
> +	if (write)
> +		flags |= FOLL_WRITE;
> +	if (force)
> +		flags |= FOLL_FORCE;
> +
> +	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);

Wouldn't it be better to just export __get_user_pages as a proper user
interface, maybe replacing get_user_pages by it entirely?

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