linux-kernel - Re: [PATCH RFC 3/3] mm, vmscan: correct prepare_kswapd

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Date:   Wed, 25 Jan 2017 10:24:08 +0800
From:   hejianet <hejianet@...il.com>
To:     Rik van Riel <riel@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Michal Hocko <mhocko@...e.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        zhong jiang <zhongjiang@...wei.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Vaishali Thakkar <vaishali.thakkar@...cle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Vlastimil Babka <vbabka@...e.cz>,
        Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH RFC 3/3] mm, vmscan: correct prepare_kswapd_sleep return
 value



On 25/01/2017 6:01 AM, Rik van Riel wrote:
> On Tue, 2017-01-24 at 15:49 +0800, Jia He wrote:
>> When there is no reclaimable pages in the zone, even the zone is
>> not balanced, we let kswapd go sleeping. That is prepare_kswapd_sleep
>> will return true in this case.
>>
>> Signed-off-by: Jia He <hejianet@...il.com>
>> ---
>>  mm/vmscan.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 7396a0a..54445e2 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -3140,7 +3140,8 @@ static bool prepare_kswapd_sleep(pg_data_t
>> *pgdat, int order, int classzone_idx)
>>  		if (!managed_zone(zone))
>>  			continue;
>>
>> -		if (!zone_balanced(zone, order, classzone_idx))
>> +		if (!zone_balanced(zone, order, classzone_idx)
>> +			&& !zone_reclaimable_pages(zone))
>>  			return false;
>>  	}
>
> This patch does the opposite of what your changelog
> says.  The above keeps kswapd running forever if
> the zone is not balanced, and there are no reclaimable
> pages.
sorry for the mistake, I will check what happened.
I tested in my local system.

B.R.
Jia
>
>