mm: numa: avoid unnecessary work on the failure path

commit eb4489f6 upstream.

If a PMD changes during a THP migration then migration aborts but the
failure path is doing more work than is necessary.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mm/migrate.c

@@ -1715,7 +1715,8 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 		putback_lru_page(page);
 		mod_zone_page_state(page_zone(page),
 			 NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR);
-		goto out_fail;
+
+		goto out_unlock;
 	}
 
 	/*
@@ -1765,6 +1766,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 	set_pmd_at(mm, haddr, pmd, entry);
 	update_mmu_cache_pmd(vma, address, &entry);
 
+out_unlock:
 	unlock_page(page);
 	put_page(page);
 	return 0;