mm: compaction: push isolate search base of compact control one pfn ahead

After isolated the current pfn will no longer be scanned and isolated if
the next round is necessary, so push the isolate_migratepages search base
of the given compact_control one step ahead.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/compaction.c b/mm/compaction.c
index 899d95638586fcc65b44d631705845bef6245be3..8f8a5525dcde569fd2d4101fa9a0666328e58e4e 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -365,8 +365,10 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
                nr_isolated++;
 
                /* Avoid isolating too much */
-               if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
+               if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
+                       ++low_pfn;
                        break;
+               }
        }
 
        acct_isolated(zone, cc);