linux-kernel - Re: [PATCH] mm: correct the comment when reclaimed pages exceed the scanned pages

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Message-ID: <593A0080.4040806@huawei.com>
Date:   Fri, 9 Jun 2017 09:57:20 +0800
From:   zhong jiang <zhongjiang@...wei.com>
To:     Minchan Kim <minchan@...nel.org>, <akpm@...ux-foundation.org>
CC:     <vinayakm.list@...il.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: correct the comment when reclaimed pages exceed the
 scanned pages

On 2017/6/8 14:46, Minchan Kim wrote:
> On Wed, Jun 07, 2017 at 04:31:06PM +0800, zhongjiang wrote:
>> The commit e1587a494540 ("mm: vmpressure: fix sending wrong events on
>> underflow") declare that reclaimed pages exceed the scanned pages due
>> to the thp reclaim. it is incorrect because THP will be spilt to normal
>> page and loop again. which will result in the scanned pages increment.
>>
>> Signed-off-by: zhongjiang <zhongjiang@...wei.com>
>> ---
>>  mm/vmpressure.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/vmpressure.c b/mm/vmpressure.c
>> index 6063581..0e91ba3 100644
>> --- a/mm/vmpressure.c
>> +++ b/mm/vmpressure.c
>> @@ -116,8 +116,9 @@ static enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,
>>  
>>  	/*
>>  	 * reclaimed can be greater than scanned in cases
>> -	 * like THP, where the scanned is 1 and reclaimed
>> -	 * could be 512
>> +	 * like reclaimed slab pages, shrink_node just add
>> +	 * reclaimed page without a related increment to
>> +	 * scanned pages.
>>  	 */
>>  	if (reclaimed >= scanned)
>>  		goto out;
> Thanks for the fixing my fault!
>
> Acked-by: Minchan Kim <minchan@...nel.org>
>
> Frankly speaking, I'm not sure we need such comment in there at the cost
> of maintainance because it would be fragile but easy to fix by above simple
> condition so I think it would be better to remove that comment but others
> might be different. So, don't have any objection.
>
>
> .
>
 Thanks

 Regards
 zhongjiang