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

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Message-ID: <20141024144101.GA28055@esperanza>
Date:	Fri, 24 Oct 2014 18:41:01 +0400
From:	Vladimir Davydov <vdavydov@...allels.com>
To:	Johannes Weiner <hannes@...xchg.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...e.cz>, <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, Oct 24, 2014 at 09:49:47AM -0400, 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>

Reviewed-by: Vladimir Davydov <vdavydov@...allels.com>

> ---
>  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
> 
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