[PATCH] vmscan: recalculate lru_pages on each shrink_slab()

[KOSAKI Motohiro]

Andrew Morton pointed out shrink_slab() may change number of reclaimable
pages (e.g. shrink_icache_memory()->prune_icache() will remove unmapped
pagecache).

So, we need to recalculate lru_pages on each shrink_slab() calling.
This patch fixes it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
---
 mm/vmscan.c |   18 ++++++++++++------
 1 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1bf9f72..1da9b14 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2612,8 +2612,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 
 	nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
 	if (nr_slab_pages0 > zone->min_slab_pages) {
-		unsigned long lru_pages = zone_reclaimable_pages(zone);
-
 		/*
 		 * shrink_slab() does not currently allow us to determine how
 		 * many pages were freed in this zone. So we take the current
@@ -2624,10 +2622,18 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 		 * Note that shrink_slab will free memory on all zones and may
 		 * take a long time.
 		 */
-		while (shrink_slab(sc.nr_scanned, gfp_mask, lru_pages) &&
-		       (zone_page_state(zone, NR_SLAB_RECLAIMABLE) + nr_pages >
-			nr_slab_pages0))
-			;
+		for (;;) {
+			unsigned long lru_pages = zone_reclaimable_pages(zone);
+
+			/* No reclaimable slab or very low memroy pressure */
+			if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages))
+				break;
+
+			/* Freed enouch memory */
+			nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
+			if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
+				break;
+		}
 
 		/*
 		 * Update nr_reclaimed by the number of slab pages we
-- 
1.6.5.2



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