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Subject: Re: [PATCH RFC 3/3] mm, vmscan: correct prepare_kswapd_sleep return
 value
To: Rik van Riel <riel@redhat.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <1485244144-13487-1-git-send-email-hejianet@gmail.com>
 <1485244144-13487-4-git-send-email-hejianet@gmail.com>
 <1485295267.15964.38.camel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Michal Hocko <mhocko@suse.com>, Mike Kravetz <mike.kravetz@oracle.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        zhong jiang <zhongjiang@huawei.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Vaishali Thakkar <vaishali.thakkar@oracle.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Mel Gorman <mgorman@techsingularity.net>,
        Vlastimil Babka <vbabka@suse.cz>, Minchan Kim <minchan@kernel.org>
From: hejianet <hejianet@gmail.com>
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Date: Wed, 25 Jan 2017 10:24:08 +0800
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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@gmail.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
>
>