On 19.08.2016 01:26, Michal Hocko wrote:
>
>>> That being said, let's wait for the feedback on this patch + linux-next.
>>> If it works out I will send a stable 4.7 patch which drops compaction
>>> feedback from should_compact_retry (turn it to the !COMPACTION version)
>>> so that 4.7 users do not suffer from the premature OOM and will ask
>>> Andrew to sneak the compaction patches to 4.8 as they fix a real issue
>>> and the risk is not really high.
>> Agreed.
>>
>>> Acked-by: Michal Hocko <mhocko@suse.com>
>> Thanks!
>>
>> -----8<-----
>> >From c4da7022e85e52f5463055cdc474656652e7a504 Mon Sep 17 00:00:00 2001
>> From: Vlastimil Babka <vbabka@suse.cz>
>> Date: Fri, 19 Aug 2016 09:40:31 +0200
>> Subject: [PATCH] mm, compaction: add the ultimate direct compaction
>>   priority-fix
>>
>> Use the MIN_COMPACT_PRIORITY alias instead of COMPACT_PRIO_SYNC_FULL to
>> disable heuristics "because this would be easier to follow and it would be
>> easier for future changes", per Michal.
>>
>> Suggested-by: Michal Hocko <mhocko@suse.cz>
>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>> Fixes: mmotm mm-compaction-add-the-ultimate-direct-compaction-priority.patch
> I guess Fixes is a bit misleading. This is not a bug it is a cleanup
> patch.
>
> Acked-by: Michal Hocko <mhocko@suse.com>
>
> Thanks!
>
>> ---
>>   mm/compaction.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index ae4f40afcca1..3e35fce2cace 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -1644,8 +1644,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
>>   		.alloc_flags = alloc_flags,
>>   		.classzone_idx = classzone_idx,
>>   		.direct_compaction = true,
>> -		.whole_zone = (prio == COMPACT_PRIO_SYNC_FULL),
>> -		.ignore_skip_hint = (prio == COMPACT_PRIO_SYNC_FULL)
>> +		.whole_zone = (prio == MIN_COMPACT_PRIORITY),
>> +		.ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY)
>>   	};
>>   	INIT_LIST_HEAD(&cc.freepages);
>>   	INIT_LIST_HEAD(&cc.migratepages);
>> @@ -1691,7 +1691,7 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
>>   								ac->nodemask) {
>>   		enum compact_result status;
>>   
>> -		if (prio > COMPACT_PRIO_SYNC_FULL
>> +		if (prio > MIN_COMPACT_PRIORITY
>>   					&& compaction_deferred(zone, order)) {
>>   			rc = max_t(enum compact_result, COMPACT_DEFERRED, rc);
>>   			continue;
>> -- 
>> 2.9.2
>>
>>
This change was in linux-next-20160823 so I ran it unmodified.

I did get an OOM, see attached.


Thanks,

Ralf-Peter


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