mm: compaction: ensure that the compaction free scanner does not move to the next...

[android-x86/kernel.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index 021a296..5c744ab 100644 (file)
--- 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