linux-kernel - Re: [PATCH v3 3/3] Prevent activation of page in madvise

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Message-ID: <20101130113540.GD15564@cmpxchg.org>
Date:	Tue, 30 Nov 2010 12:35:40 +0100
From:	Johannes Weiner <hannes@...xchg.org>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ben Gamari <bgamari.foss@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Nick Piggin <npiggin@...nel.dk>, Mel Gorman <mel@....ul.ie>,
	Wu Fengguang <fengguang.wu@...el.com>
Subject: Re: [PATCH v3 3/3] Prevent activation of page in madvise_dontneed

On Tue, Nov 30, 2010 at 12:23:21AM +0900, Minchan Kim wrote:
> Now zap_pte_range alwayas activates pages which are pte_young &&
> !VM_SequentialReadHint(vma). But in case of calling MADV_DONTNEED,
> it's unnecessary since the page wouldn't use any more.
> 
> Signed-off-by: Minchan Kim <minchan.kim@...il.com>
> Acked-by: Rik van Riel <riel@...hat.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Nick Piggin <npiggin@...nel.dk>
> Cc: Mel Gorman <mel@....ul.ie>
> Cc: Wu Fengguang <fengguang.wu@...el.com>
> 
> Changelog since v2:
>  - remove unnecessary description
> Changelog since v1: 
>  - change word from promote to activate
>  - add activate argument to zap_pte_range and family function
> 
> ---
>  include/linux/mm.h |    4 ++--
>  mm/madvise.c       |    4 ++--
>  mm/memory.c        |   38 +++++++++++++++++++++++---------------
>  mm/mmap.c          |    4 ++--
>  4 files changed, 29 insertions(+), 21 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index e097df6..6032881 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -779,11 +779,11 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>  int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
>  		unsigned long size);
>  unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
> -		unsigned long size, struct zap_details *);
> +		unsigned long size, struct zap_details *, bool activate);

I would prefer naming the parameter 'ignore_references' or something
similar, so that it reflects the immediate effect on the zappers'
behaviour, not what mark_page_accessed() might end up doing.

Other than that, the patch looks good to me.

	Hannes
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