linux-kernel - Re: [PATCH] memcg: clean up soft_limit

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Date:	Tue, 13 Dec 2011 17:00:12 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	Hillf Danton <dhillf@...il.com>, Hugh Dickins <hughd@...gle.com>,
	Balbir Singh <bsingharora@...il.com>,
	David Rientjes <rientjes@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] memcg: clean up soft_limit_tree properly new

On Mon, 12 Dec 2011 15:09:35 +0100
Michal Hocko <mhocko@...e.cz> wrote:

> And a follow up patch for the proper clean up:
> ---
> >From 4b9f5a1e88496af9f336d1ef37cfdf3754a3ba48 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@...e.cz>
> Date: Mon, 12 Dec 2011 15:04:18 +0100
> Subject: [PATCH] memcg: clean up soft_limit_tree properly
> 
> If we are not able to allocate tree nodes for all NUMA nodes then we
> should better clean up those that were allocated otherwise we will leak
> a memory.
> 
> Signed-off-by: Michal Hocko <mhocko@...e.cz>
> ---
>  mm/memcontrol.c |   12 +++++++++++-
>  1 files changed, 11 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6aff93c..838d812 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4874,7 +4874,7 @@ static int mem_cgroup_soft_limit_tree_init(void)
>  			tmp = -1;
>  		rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
>  		if (!rtpn)
> -			return 1;
> +			goto err_cleanup;
>  
>  		soft_limit_tree.rb_tree_per_node[node] = rtpn;
>  
> @@ -4885,6 +4885,16 @@ static int mem_cgroup_soft_limit_tree_init(void)
>  		}
>  	}
>  	return 0;
> +
> +err_cleanup:
> +	for_each_node_state(node, N_POSSIBLE) {
> +		if (!soft_limit_tree.rb_tree_per_node[node])
> +			break;
> +		kfree(soft_limit_tree.rb_tree_per_node[node]);
> +		soft_limit_tree.rb_tree_per_node[node] = NULL;
> +	}
> +	return 1;
> +
>  }

afacit the kernel never frees the soft_limit_tree.rb_tree_per_node[]
entries on the mem_cgroup_destroy() path.  Bug?
--
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