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>

diff --git a/mm/compaction.c b/mm/compaction.c
index dcb058bd76c4272a8b972e8b7089647bcc7aadb5..38ce48805c0803874d5a674b25f07543304873df 100644 (file)
--- 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;
                }