1 files changed, 12 insertions, 1 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index cf7086c6dc07..9b94eaf537e4 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -144,9 +144,20 @@ static void isolate_freepages(struct zone *zone,
         int nr_freepages = cc->nr_freepages;
         struct list_head *freelist = &cc->freepages;
 
+        /*
+         * Initialise the free scanner. The starting point is where we last
+         * scanned from (or the end of the zone if starting). The low point
+         * is the end of the pageblock the migration scanner is using.
+         */
         pfn = cc->free_pfn;
         low_pfn = cc->migrate_pfn + pageblock_nr_pages;
-        high_pfn = low_pfn;
+
+        /*
+         * Take care that if the migration scanner is at the end of the zone
+         * that the free scanner does not accidentally move to the next zone
+         * in the next isolation cycle.
+         */
+        high_pfn = min(low_pfn, pfn);
 
         /*
          * Isolate free pages until enough are available to migrate the