1 files changed, 31 insertions, 19 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index cd5dc3faaa57..4390a8d5be41 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -442,16 +442,8 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
 	if (memcg && (!memcg_kmem_enabled() || !mem_cgroup_online(memcg)))
 		return 0;
 
-	if (!down_read_trylock(&shrinker_rwsem)) {
-		/*
-		 * If we would return 0, our callers would understand that we
-		 * have nothing else to shrink and give up trying. By returning
-		 * 1 we keep it going and assume we'll be able to shrink next
-		 * time.
-		 */
-		freed = 1;
+	if (!down_read_trylock(&shrinker_rwsem))
 		goto out;
-	}
 
 	list_for_each_entry(shrinker, &shrinker_list, list) {
 		struct shrink_control sc = {
@@ -3547,16 +3539,21 @@ kswapd_try_sleep:
 }
 
 /*
- * A zone is low on free memory, so wake its kswapd task to service it.
+ * A zone is low on free memory or too fragmented for high-order memory.  If
+ * kswapd should reclaim (direct reclaim is deferred), wake it up for the zone's
+ * pgdat.  It will wake up kcompactd after reclaiming memory.  If kswapd reclaim
+ * has failed or is not needed, still wake up kcompactd if only compaction is
+ * needed.
  */
-void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
+void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
+		   enum zone_type classzone_idx)
 {
 	pg_data_t *pgdat;
 
 	if (!managed_zone(zone))
 		return;
 
-	if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL))
+	if (!cpuset_zone_allowed(zone, gfp_flags))
 		return;
 	pgdat = zone->zone_pgdat;
 	pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat,
@@ -3565,14 +3562,23 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
 	if (!waitqueue_active(&pgdat->kswapd_wait))
 		return;
 
-	/* Hopeless node, leave it to direct reclaim */
-	if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
-		return;
-
-	if (pgdat_balanced(pgdat, order, classzone_idx))
+	/* Hopeless node, leave it to direct reclaim if possible */
+	if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ||
+	    pgdat_balanced(pgdat, order, classzone_idx)) {
+		/*
+		 * There may be plenty of free memory available, but it's too
+		 * fragmented for high-order allocations.  Wake up kcompactd
+		 * and rely on compaction_suitable() to determine if it's
+		 * needed.  If it fails, it will defer subsequent attempts to
+		 * ratelimit its work.
+		 */
+		if (!(gfp_flags & __GFP_DIRECT_RECLAIM))
+			wakeup_kcompactd(pgdat, order, classzone_idx);
 		return;
+	}
 
-	trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, classzone_idx, order);
+	trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, classzone_idx, order,
+				      gfp_flags);
 	wake_up_interruptible(&pgdat->kswapd_wait);
 }
 
@@ -3877,7 +3883,13 @@ int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
  */
 int page_evictable(struct page *page)
 {
-	return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
+	int ret;
+
+	/* Prevent address_space of inode and swap cache from being freed */
+	rcu_read_lock();
+	ret = !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
+	rcu_read_unlock();
+	return ret;
 }
 
 #ifdef CONFIG_SHMEM