mm/compaction: check migrate_pages's return value instead of list_empty()

Many migrate_page's caller check return value instead of list_empy by
cf608ac19c ("mm: compaction: fix COMPACTPAGEFAILED counting").  This patch
makes compaction's migrate_pages consistent with others.  This patch
should not change old behavior.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index dcb058bd76c4..38ce48805c08 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -494,12 +494,13 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 
         while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
                 unsigned long nr_migrate, nr_remaining;
+                int err;
 
                 if (!isolate_migratepages(zone, cc))
                         continue;
 
                 nr_migrate = cc->nr_migratepages;
-                migrate_pages(&cc->migratepages, compaction_alloc,
+                err = migrate_pages(&cc->migratepages, compaction_alloc,
                                 (unsigned long)cc, false,
                                 cc->sync);
                 update_nr_listpages(cc);
@@ -513,7 +514,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
                                                 nr_remaining);
 
                 /* Release LRU pages not migrated */
-                if (!list_empty(&cc->migratepages)) {
+                if (err) {
                         putback_lru_pages(&cc->migratepages);
                         cc->nr_migratepages = 0;
                 }