linux-kernel - Re: [patch] mm, memcg: avoid unnecessary function call when memcg is disabled fix

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Date:	Wed, 21 Nov 2012 13:11:11 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>,
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [patch] mm, memcg: avoid unnecessary function call when memcg
 is disabled fix

(2012/11/21 11:48), David Rientjes wrote:
> Move the check for !mm out of line as suggested by Andrew.
>
> Signed-off-by: David Rientjes <rientjes@...gle.com>

Thank you very much !

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


> ---
>   include/linux/memcontrol.h |    2 +-
>   mm/memcontrol.c            |    3 +++
>   2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -185,7 +185,7 @@ void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
>   static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
>   					     enum vm_event_item idx)
>   {
> -	if (mem_cgroup_disabled() || !mm)
> +	if (mem_cgroup_disabled())
>   		return;
>   	__mem_cgroup_count_vm_event(mm, idx);
>   }
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1021,6 +1021,9 @@ void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
>   {
>   	struct mem_cgroup *memcg;
>
> +	if (!mm)
> +		return;
> +
>   	rcu_read_lock();
>   	memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
>   	if (unlikely(!memcg))
>


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