linux-kernel - Re: [patch 1/3] mm: memcontrol: remove bogus NULL check after mem_cgroup_from

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Message-ID: <20141024182911.GA18956@dhcp22.suse.cz>
Date:	Fri, 24 Oct 2014 20:29:11 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Vladimir Davydov <vdavydov@...allels.com>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] mm: memcontrol: remove bogus NULL check after
 mem_cgroup_from_task()

On Fri 24-10-14 09:49:47, Johannes Weiner wrote:
> That function acts like a typecast - unless NULL is passed in, no NULL
> can come out.  task_in_mem_cgroup() callers don't pass NULL tasks.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

Thanks and sorry about my bogus version earlier today.

Acked-by: Michal Hocko <mhocko@...e.cz

> ---
>  mm/memcontrol.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 23cf27cca370..bdf8520979cf 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1335,7 +1335,7 @@ static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
>  bool task_in_mem_cgroup(struct task_struct *task,
>  			const struct mem_cgroup *memcg)
>  {
> -	struct mem_cgroup *curr = NULL;
> +	struct mem_cgroup *curr;
>  	struct task_struct *p;
>  	bool ret;
>  
> @@ -1351,8 +1351,7 @@ bool task_in_mem_cgroup(struct task_struct *task,
>  		 */
>  		rcu_read_lock();
>  		curr = mem_cgroup_from_task(task);
> -		if (curr)
> -			css_get(&curr->css);
> +		css_get(&curr->css);
>  		rcu_read_unlock();
>  	}
>  	/*
> -- 
> 2.1.2
> 

-- 
Michal Hocko
SUSE Labs
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