[PATCH 4.6 073/121] mm/compaction.c: fix zoneindex in kcompactd()

Greg Kroah-Hartman
2016-06-05T21:57:57Z

From: Chen Feng <puck.chen@hisilicon.com>

commit 6cd9dc3e75078ef646076fa63adfb9b85ced0b66 upstream.

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: accf62422b3a ("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>
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/compaction.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1742,7 +1742,7 @@ static bool kcompactd_node_suitable(pg_d
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))
@@ -1777,7 +1777,7 @@ static void kcompactd_do_work(pg_data_t
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];