In some cases migrate_pages could return zero while still leaving a few
pages in the pagelist (and some caller wouldn't notice it has to call
putback_lru_pages after commit cf608ac1 ("mm: compaction: fix
COMPACTPAGEFAILED counting")).

Add one missing putback_lru_pages not added by commit cf608ac1 ("mm:
compaction: fix COMPACTPAGEFAILED counting").
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>