[PATCH mmotm] memcg: check if first threshold crossed

[Kirill A. Shutemov]

There is a bug in memory thresholds code. We don't check if first
threshold (array index 0) was crossed down. This patch fixes it.

Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
 mm/memcontrol.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 41e00c2..a443c30 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3252,7 +3252,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
 	 * If none of thresholds below usage is crossed, we read
 	 * only one element of the array here.
 	 */
-	for (; i > 0 && unlikely(t->entries[i].threshold > usage); i--)
+	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
 		eventfd_signal(t->entries[i].eventfd, 1);
 
 	/* i = current_threshold + 1 */
-- 
1.6.5.8

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