Patchwork [2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

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Submitter Johannes Weiner
Date Feb. 28, 2017, 9:40 p.m.
Message ID <20170228214007.5621-3-hannes@cmpxchg.org>
Download mbox | patch
Permalink /patch/9597757/
State New
Headers show

Comments

Johannes Weiner - Feb. 28, 2017, 9:40 p.m.
PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
all free pages in each zone fall below half the min watermark. During
the summation, we want to exclude zones that don't have reclaimables.
Checking the same pgdat over and over again doesn't make sense.

Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/vmscan.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
Michal Hocko - March 1, 2017, 3:02 p.m.
On Tue 28-02-17 16:40:00, Johannes Weiner wrote:
> PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
> all free pages in each zone fall below half the min watermark. During
> the summation, we want to exclude zones that don't have reclaimables.
> Checking the same pgdat over and over again doesn't make sense.
> 
> Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/vmscan.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 407b27831ff7..f006140f58c6 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2838,8 +2838,10 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
>  
>  	for (i = 0; i <= ZONE_NORMAL; i++) {
>  		zone = &pgdat->node_zones[i];
> -		if (!managed_zone(zone) ||
> -		    pgdat_reclaimable_pages(pgdat) == 0)
> +		if (!managed_zone(zone))
> +			continue;
> +
> +		if (!zone_reclaimable_pages(zone))
>  			continue;
>  
>  		pfmemalloc_reserve += min_wmark_pages(zone);
> -- 
> 2.11.1
Hillf Danton - March 2, 2017, 3:25 a.m.
On March 01, 2017 5:40 AM Johannes Weiner wrote: 
> 
> PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
> all free pages in each zone fall below half the min watermark. During
> the summation, we want to exclude zones that don't have reclaimables.
> Checking the same pgdat over and over again doesn't make sense.
> 
> Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

Patch

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 407b27831ff7..f006140f58c6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2838,8 +2838,10 @@  static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
 
 	for (i = 0; i <= ZONE_NORMAL; i++) {
 		zone = &pgdat->node_zones[i];
-		if (!managed_zone(zone) ||
-		    pgdat_reclaimable_pages(pgdat) == 0)
+		if (!managed_zone(zone))
+			continue;
+
+		if (!zone_reclaimable_pages(zone))
 			continue;
 
 		pfmemalloc_reserve += min_wmark_pages(zone);