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Date: Fri, 16 Nov 2012 09:09:37 -0500
From: Rik van Riel <riel@redhat.com>
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Subject: Re: [PATCH 07/43] mm: numa: Support NUMA hinting page faults from
 gup/gup_fast
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To: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Andrea Arcangeli <aarcange@redhat.com>, Ingo Molnar <mingo@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>, Hugh Dickins <hughd@google.com>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>

On 11/16/2012 06:22 AM, Mel Gorman wrote:
> From: Andrea Arcangeli <aarcange@redhat.com>
>
> Introduce FOLL_NUMA to tell follow_page to check
> pte/pmd_numa. get_user_pages must use FOLL_NUMA, and it's safe to do
> so because it always invokes handle_mm_fault and retries the
> follow_page later.
>
> KVM secondary MMU page faults will trigger the NUMA hinting page
> faults through gup_fast -> get_user_pages -> follow_page ->
> handle_mm_fault.
>
> Other follow_page callers like KSM should not use FOLL_NUMA, or they
> would fail to get the pages if they use follow_page instead of
> get_user_pages.
>
> [ This patch was picked up from the AutoNUMA tree. ]
>
> Originally-by: Andrea Arcangeli <aarcange@redhat.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Cc: Rik van Riel <riel@redhat.com>
> [ ported to this tree. ]
> Signed-off-by: Ingo Molnar <mingo@kernel.org>

Reviewed-by: Rik van Riel <riel@redhat.com>


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