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From: Michal Hocko <mhocko@suse.cz>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vladimir Davydov <vdavydov@parallels.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [patch 1/3] mm: memcontrol: remove bogus NULL check after mem_cgroup_from_task()
Date: Fri, 24 Oct 2014 20:29:11 +0200	[thread overview]
Message-ID: <20141024182911.GA18956@dhcp22.suse.cz> (raw)
In-Reply-To: <1414158589-26094-1-git-send-email-hannes@cmpxchg.org>

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@cmpxchg.org>

Thanks and sorry about my bogus version earlier today.

Acked-by: Michal Hocko <mhocko@suse.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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      parent reply	other threads:[~2014-10-24 18:29 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-24 13:49 Johannes Weiner
2014-10-24 13:49 ` [patch 2/3] mm: memcontrol: pull the NULL check from __mem_cgroup_same_or_subtree() Johannes Weiner
2014-10-24 14:49   ` Vladimir Davydov
2014-10-24 18:30   ` Michal Hocko
2014-10-24 13:49 ` [patch 3/3] mm: memcontrol: drop bogus RCU locking from mem_cgroup_same_or_subtree() Johannes Weiner
2014-10-24 15:22   ` Vladimir Davydov
2014-10-24 18:41   ` Michal Hocko
2014-10-24 14:41 ` [patch 1/3] mm: memcontrol: remove bogus NULL check after mem_cgroup_from_task() Vladimir Davydov
2014-10-24 18:29 ` Michal Hocko [this message]

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