Hi Minchan,

FYI, there are new compile warnings show up in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm
head:   d28e1f373a79e532eecbe6b17beeb4d2052c1a52
commit: 29cfd54de3204fe1b8b6a4ea744a21b43f3e00fa [146/246] mm: support MIGRATE_DISCARD
config: i386-randconfig-k920 (attached as .config)

All error/warnings:

mm/migrate.c: In function 'migrate_pages':
mm/migrate.c:827:5: warning: 'ttu_flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
mm/migrate.c:701:17: note: 'ttu_flags' was declared here

vim +827 mm/migrate.c
   817	
   818		file = page_is_file_cache(page);
   819		ttu_flags = TTU_IGNORE_ACCESS;
   820	retry:
   821		if (!(mode & MIGRATE_DISCARD) || !file || PageDirty(page))
   822			ttu_flags |= (TTU_MIGRATION | TTU_IGNORE_MLOCK);
   823		else
   824			discard_mode = true;
   825	
   826		/* Establish migration ptes or remove ptes */
 > 827		rc = try_to_unmap(page, ttu_flags);
   828	
   829	skip_unmap:
   830		if (rc == SWAP_SUCCESS) {
   831			if (!discard_mode) {
   832				rc = move_to_new_page(newpage, page,
   833						remap_swapcache, mode);
   834			} else {
   835				rc = discard_page(page);
   836				goto uncharge;
   837			}

---
0-DAY kernel build testing backend         Open Source Technology Centre
Fengguang Wu <wfg@linux.intel.com>                     Intel Corporation