mm/compaction.c: fix zoneindex in kcompactd()

While testing the kcompactd in my platform 3G MEM only DMA ZONE.  I
found the kcompactd never wakeup.  It seems the zoneindex has already
minus 1 before.  So the traverse here should be <=.

It fixes a regression where kswapd could previously compact, but
kcompactd not.  Not a crash fix though.

[akpm@linux-foundation.org: fix kcompactd_do_work() as well, per Hugh]
Link: http://lkml.kernel.org/r/1463659121-84124-1-git-send-email-puck.chen@hisilicon.com
Fixes: accf624 ("mm, kswapd: replace kswapd compaction with waking up kcompactd")
Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zhuangluan Su <suzhuangluan@hisilicon.com>
Cc: Yiping Xu <xuyiping@hisilicon.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/compaction.c

@@ -1862,7 +1862,7 @@ static bool kcompactd_node_suitable(pg_data_t *pgdat)
 	struct zone *zone;
 	enum zone_type classzone_idx = pgdat->kcompactd_classzone_idx;
 
-	for (zoneid = 0; zoneid < classzone_idx; zoneid++) {
+	for (zoneid = 0; zoneid <= classzone_idx; zoneid++) {
 		zone = &pgdat->node_zones[zoneid];
 
 		if (!populated_zone(zone))
@@ -1897,7 +1897,7 @@ static void kcompactd_do_work(pg_data_t *pgdat)
 							cc.classzone_idx);
 	count_vm_event(KCOMPACTD_WAKE);
 
-	for (zoneid = 0; zoneid < cc.classzone_idx; zoneid++) {
+	for (zoneid = 0; zoneid <= cc.classzone_idx; zoneid++) {
 		int status;
 
 		zone = &pgdat->node_zones[zoneid];