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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/compaction.c b/mm/compaction.c
index 1253d7ac332b5031515b5a2f3e9ba4bb4956a27f..e6670c34eb4950b8953eeedbe02fe52f29ec84bf 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);