linux-kernel - Re: [PATCH v2] mm: Allocate shrinker

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Message-ID: <20200131154735.GA4520@dhcp22.suse.cz>
Date:   Fri, 31 Jan 2020 16:47:35 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     David Hildenbrand <david@...hat.com>, akpm@...ux-foundation.org,
        hannes@...xchg.org, shakeelb@...gle.com, vdavydov.dev@...il.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm: Allocate shrinker_map on appropriate NUMA node

On Fri 31-01-20 18:00:51, Kirill Tkhai wrote:
[...]
> @@ -333,8 +333,9 @@ static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg,
>  		/* Not yet online memcg */
>  		if (!old)
>  			return 0;
> -
> -		new = kvmalloc(sizeof(*new) + size, GFP_KERNEL);
> +		/* See comment in alloc_mem_cgroup_per_node_info()*/
> +		tmp = node_state(nid, N_NORMAL_MEMORY) ? nid : NUMA_NO_NODE;
> +		new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, tmp);
>  		if (!new)
>  			return -ENOMEM;

I do not think this is a good pattern to copy. Why cannot you simply use
kvmalloc_node with the given node? The allocator should fallback to the
closest node if the given one doesn't have any memory.
-- 
Michal Hocko
SUSE Labs