vmscan: check high watermark after shrink zone
Kswapd checks that zone has sufficient pages free via zone_watermark_ok().
If any zone doesn't have enough pages, we set all_zones_ok to zero.
!all_zone_ok makes kswapd retry rather than sleeping.
I think the watermark check before shrink_zone() is pointless. Only after
kswapd has tried to shrink the zone is the check meaningful.
Move the check to after the call to shrink_zone().
[akpm@linux-foundation.org: fix comment, layout]
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index c26986c..96ebe66 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2060,9 +2060,6 @@
priority != DEF_PRIORITY)
continue;
- if (!zone_watermark_ok(zone, order,
- high_wmark_pages(zone), end_zone, 0))
- all_zones_ok = 0;
temp_priority[i] = priority;
sc.nr_scanned = 0;
note_zone_scanning_priority(zone, priority);
@@ -2102,13 +2099,18 @@
total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
sc.may_writepage = 1;
- /*
- * We are still under min water mark. it mean we have
- * GFP_ATOMIC allocation failure risk. Hurry up!
- */
- if (!zone_watermark_ok(zone, order, min_wmark_pages(zone),
- end_zone, 0))
- has_under_min_watermark_zone = 1;
+ if (!zone_watermark_ok(zone, order,
+ high_wmark_pages(zone), end_zone, 0)) {
+ all_zones_ok = 0;
+ /*
+ * We are still under min water mark. This
+ * means that we have a GFP_ATOMIC allocation
+ * failure risk. Hurry up!
+ */
+ if (!zone_watermark_ok(zone, order,
+ min_wmark_pages(zone), end_zone, 0))
+ has_under_min_watermark_zone = 1;
+ }
}
if (all_zones_ok)