linux-kernel - PFs on pages pinned with get_user

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Date:	Thu, 29 Jan 2009 09:05:07 +0100
From:	Frank Mehnert <Frank.Mehnert@....COM>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: PFs on pages pinned with get_user_pages()

Hi,

please could someone explain me under which circumstances a pagefault,
either generated from kernel code or from userland code, can occur on
pages which are pinned with get_user_pages()?

So far my understanding was that this can _never_ happen but I seems to
be wrong. Under high memory pressure I get PFs on such pages raised from
kernel code and the PFs are handled by do_swap_page(). When this happens,
page_count is 3 but page_mapped() returns false.

Thanks in advance,

Frank
-- 
Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/

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