mm: compaction: do not compact pgdat for order-0

If kswapd was reclaiming for a high order and resets it to 0 due to
fragmentation it will still call compact_pgdat.  For the most part, this
will fail a compaction_suitable() test and not compact but it is
unnecessarily sloppy.  It could be fixed in the caller but fix it in the
API instead.

[[email protected]: pointed out that it was a potential problem]
Signed-off-by: Mel Gorman <[email protected]>
Cc: Hillf Danton <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/compaction.c b/mm/compaction.c
index 05ccb4cc0bdb984dc2613461703587ec199804cd..c43789388cd8667536bfd9644a5bbe2cd0d35f3e 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1131,6 +1131,9 @@ void compact_pgdat(pg_data_t *pgdat, int order)
                .sync = false,
        };
 
+       if (!order)
+               return;
+
        __compact_pgdat(pgdat, &cc);
 }