linux-kernel - Re: [PATCH] prevent to reclaim anon page of lumpy reclaim for no swap space

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Message-ID: <28c262360906250730h7f8240c2mb1411ef147b239b2@mail.gmail.com>
Date:	Thu, 25 Jun 2009 23:30:11 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-mm <linux-mm@...ck.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] prevent to reclaim anon page of lumpy reclaim for no swap 
	space

On Thu, Juna 25, 2009 at 11:09 PM, Rik van Riel<riel@...hat.com> wrote:
> Minchan Kim wrote:
>>
>> This patch prevent to reclaim anon page in case of no swap space.
>> VM already prevent to reclaim anon page in various place.
>> But it doesnt't prevent it for lumpy reclaim.
>>
>> It shuffles lru list unnecessary so that it is pointless.
>> Signed-off-by: Minchan Kim <minchan.kim@...il.com>
>> ---
>>  mm/vmscan.c |    6 ++++++
>>  1 files changed, 6 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 026f452..fb401fe 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -830,7 +830,13 @@ int __isolate_lru_page(struct page *page, int mode,
>> int file)
>>         * When this function is being called for lumpy reclaim, we
>>         * initially look into all LRU pages, active, inactive and
>>         * unevictable; only give shrink_page_list evictable pages.
>> +
>> +        * If we don't have enough swap space, reclaiming of anon page
>> +        * is pointless.
>>         */
>> +       if (nr_swap_pages <= 0 && PageAnon(page))
>> +               return ret;
>> +
>
> Should that be something like this:
>
>        if (nr_swap_pages <= 0 && (PageAnon(page) && !PageSwapCache(page)))
>
> We can still reclaim anonymous pages that already have
> a swap slot assigned to them.

Yes. I missed that.
Thanks for careful review. Rik. :)

>
> --
> All rights reversed.
>



-- 
Kinds regards,
Minchan Kim
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