Re: [PATCH 5/5] mm: memcg discount pages under softlimit from per-zone reclaimable_pages

[Ying Han <yinghan@google.com>]

On Sun, Jun 17, 2012 at 7:58 PM, Kamezawa Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
> (2012/06/07 3:24), Ying Han wrote:
>> The function zone_reclaimable() marks zone->all_unreclaimable based on
>> per-zone pages_scanned and reclaimable_pages. If all_unreclaimable is true,
>> alloc_pages could go to OOM instead of getting stuck in page reclaim.
>>
>> In memcg kernel, cgroup under its softlimit is not targeted under global
>> reclaim. So we need to remove those pages from reclaimable_pages, otherwise
>> it will cause reclaim mechanism to get stuck trying to reclaim from
>> all_unreclaimable zone.
>>
>> Signed-off-by: Ying Han<yinghan@google.com>
>> ---
>>   mm/vmscan.c |   24 ++++++++++++++++++------
>>   1 files changed, 18 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 65febc1..163b197 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -3142,14 +3142,26 @@ unsigned long global_reclaimable_pages(void)
>>
>>   unsigned long zone_reclaimable_pages(struct zone *zone)
>>   {
>> -     int nr;
>> +     int nr = 0;
>> +     struct mem_cgroup *memcg;
>>
>> -     nr = zone_page_state(zone, NR_ACTIVE_FILE) +
>> -          zone_page_state(zone, NR_INACTIVE_FILE);
>> +     memcg = mem_cgroup_iter(NULL, NULL, NULL);
>> +     do {
>> +             struct mem_cgroup_zone mz = {
>> +                     .mem_cgroup = memcg,
>> +                     .zone = zone,
>> +             };
>>
>> -     if (nr_swap_pages>  0)
>> -             nr += zone_page_state(zone, NR_ACTIVE_ANON) +
>> -                   zone_page_state(zone, NR_INACTIVE_ANON);
>> +             if (should_reclaim_mem_cgroup(memcg)) {
>> +                     nr += zone_nr_lru_pages(&mz, LRU_INACTIVE_FILE) +
>> +                           zone_nr_lru_pages(&mz, LRU_ACTIVE_FILE);
>> +
>> +                     if (nr_swap_pages>  0)
>> +                             nr += zone_nr_lru_pages(&mz, LRU_ACTIVE_ANON) +
>> +                                   zone_nr_lru_pages(&mz, LRU_INACTIVE_ANON);
>> +             }
>> +             memcg = mem_cgroup_iter(NULL, memcg, NULL);
>> +     } while (memcg);
>>
>
> Shouldn't you handle 'ignore_softlimit' case ?
> Anyway, Kosaki-san is now trying to modify zone->all_unreclaimable etc..
> we need to check it with softlimit context.

Yes, I am about to post the next version which I included Kosaki's
patch as replacement

Thanks ~

--Ying

>
> Thanks,
> -Kame
>
>

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