linux-kernel - Re: [PATCH 6/6] memcg: do not tweak node in alloc_mem_cgroup_per_node

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Message-ID: <634987e7-27c0-bca5-30cd-de7a5ede30cd@redhat.com>
Date:   Thu, 27 Jan 2022 13:50:33 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        Alexey Makhalov <amakhalov@...are.com>,
        Dennis Zhou <dennis@...nel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Oscar Salvador <osalvador@...e.de>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Nico Pache <npache@...hat.com>,
        Wei Yang <richard.weiyang@...il.com>,
        Rafael Aquini <raquini@...hat.com>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH 6/6] memcg: do not tweak node in
 alloc_mem_cgroup_per_node_info

On 27.01.22 09:53, Michal Hocko wrote:
> From: Wei Yang <richard.weiyang@...il.com>
> 
> alloc_mem_cgroup_per_node_info is allocated for each possible node and
> this used to be a problem because not !node_online nodes didn't have
> appropriate data structure allocated. This has changed by "mm: handle
> uninitialized numa nodes gracefully" so we can drop the special casing
> here.
> 
> Signed-off-by: Wei Yang <richard.weiyang@...il.com>
> Signed-off-by: Michal Hocko <mhocko@...e.com>
> ---
>  mm/memcontrol.c | 14 ++------------
>  1 file changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 09d342c7cbd0..8b3f9eef4c65 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5067,18 +5067,8 @@ struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
>  static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
>  {
>  	struct mem_cgroup_per_node *pn;
> -	int tmp = node;
> -	/*
> -	 * This routine is called against possible nodes.
> -	 * But it's BUG to call kmalloc() against offline node.
> -	 *
> -	 * TODO: this routine can waste much memory for nodes which will
> -	 *       never be onlined. It's better to use memory hotplug callback
> -	 *       function.
> -	 */
> -	if (!node_state(node, N_NORMAL_MEMORY))
> -		tmp = -1;
> -	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
> +
> +	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, node);
>  	if (!pn)
>  		return 1;
>  

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb