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

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

[Ying Han]

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);
 
 	return nr;
 }
-- 
1.7.7.3

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

[Kamezawa Hiroyuki]

(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.

Thanks,
-Kame


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

[Ying Han]

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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