thp: change deferred_split_count() to return number of THP in queue

[mirror_ubuntu-artful-kernel.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 253a25e007d71eb9052e06c7383768f12247728b..7aae721145832e8fc0c66c1862141523aa649fff 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3465,12 +3465,7 @@ static unsigned long deferred_split_count(struct shrinker *shrink,
                struct shrink_control *sc)
 {
        struct pglist_data *pgdata = NODE_DATA(sc->nid);
-       /*
-        * Split a page from split_queue will free up at least one page,
-        * at most HPAGE_PMD_NR - 1. We don't track exact number.
-        * Let's use HPAGE_PMD_NR / 2 as ballpark.
-        */
-       return ACCESS_ONCE(pgdata->split_queue_len) * HPAGE_PMD_NR / 2;
+       return ACCESS_ONCE(pgdata->split_queue_len);
 }
 
 static unsigned long deferred_split_scan(struct shrinker *shrink,
@@ -3511,7 +3506,13 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
        list_splice_tail(&list, &pgdata->split_queue);
        spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
 
-       return split * HPAGE_PMD_NR / 2;
+       /*
+        * Stop shrinker if we didn't split any page, but the queue is empty.
+        * This can happen if pages were freed under us.
+        */
+       if (!split && list_empty(&pgdata->split_queue))
+               return SHRINK_STOP;
+       return split;
 }
 
 static struct shrinker deferred_split_shrinker = {