linux-kernel - Re: virt_to_page for userspace pointers

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Date:	Sun, 13 Feb 2011 15:24:55 -0500
From:	Nikolaus Rath <Nikolaus@...h.org>
To:	Brice Goglin <Brice.Goglin@...-lyon.org>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: virt_to_page for userspace pointers

On 02/05/2011 04:36 PM, Brice Goglin wrote:
>> Is there an equivalent function to virt_to_page (and virt_to_phys) that
>> works with userspace pointers? Or do I have to manually walk through the
>> page tables? In the later case, are there any examples of this kind of
>> search that I could use as a basis?
>>   
> 
> You probably want get_user_pages() (or get_user_pages_fast()).

Thanks for the pointer, that already helped a lot!

I would, however, prefer a more primitive function that just gives me
the struct page without locking it. And if the page is swapped out, I'd
rather get a NULL pointer than having a page frame allocated.  Is there
anything like that?

Thanks,

   -Nikolaus

-- 
 »Time flies like an arrow, fruit flies like a Banana.«

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