[PATCH mmotm] memcg: check if first threshold crossed

[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@shutemov.name>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 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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Re: [PATCH mmotm] memcg: check if first threshold crossed

[KAMEZAWA Hiroyuki]

On Thu, 11 Feb 2010 01:55:23 +0200
"Kirill A. Shutemov" <kirill@shutemov.name> wrote:

> 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@shutemov.name>
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: Pavel Emelyanov <xemul@openvz.org>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

> ---
>  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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> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
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> 

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