Message-ID: <50AC545F.5080303@jp.fujitsu.com>
Date: Wed, 21 Nov 2012 13:11:11 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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To: David Rientjes <rientjes@google.com>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        Hugh Dickins <hughd@google.com>, linux-kernel@vger.kernel.org,
        cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, memcg: avoid unnecessary function call when memcg
 is disabled fix
References: <alpine.DEB.2.00.1211191741060.24618@chino.kir.corp.google.com> <20121120134932.055bc192.akpm@linux-foundation.org> <50AC282A.4070309@jp.fujitsu.com> <alpine.DEB.2.00.1211201847450.2278@chino.kir.corp.google.com>
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(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@google.com>

Thank you very much !

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