linux-kernel - Re: [PATCH 1/2] mm: memcontrol: basic memory statistics in cgroup2 memory controller

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Message-Id: <20160113144930.b20ed63f1c6a28730f66eccd@linux-foundation.org>
Date:	Wed, 13 Jan 2016 14:49:30 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Michal Hocko <mhocko@...e.cz>,
	Vladimir Davydov <vdavydov@...tuozzo.com>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-team@...com
Subject: Re: [PATCH 1/2] mm: memcontrol: basic memory statistics in cgroup2
 memory controller

On Wed, 13 Jan 2016 17:01:08 -0500 Johannes Weiner <hannes@...xchg.org> wrote:

> Provide a cgroup2 memory.stat that provides statistics on LRU memory
> and fault event counters. More consumers and breakdowns will follow.
> 
> ...
>
> @@ -5095,6 +5107,46 @@ static int memory_events_show(struct seq_file *m, void *v)
>  	return 0;
>  }
>  
> +static int memory_stat_show(struct seq_file *m, void *v)
> +{
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	int i;
> +
> +	/* Memory consumer totals */
> +
> +	seq_printf(m, "anon %lu\n",
> +		   tree_stat(memcg, MEM_CGROUP_STAT_RSS) * PAGE_SIZE);

Is there any reason why this won't overflow a longword on 32-bit?

> +	seq_printf(m, "file %lu\n",
> +		   tree_stat(memcg, MEM_CGROUP_STAT_CACHE) * PAGE_SIZE);
> +
> +	/* Per-consumer breakdowns */
> +
> +	for (i = 0; i < NR_LRU_LISTS; i++) {
> +		struct mem_cgroup *mi;
> +		unsigned long val = 0;
> +
> +		for_each_mem_cgroup_tree(mi, memcg)
> +			val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE;
> +		seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i], val);
> +	}
> +
> +	seq_printf(m, "file_mapped %lu\n",
> +		   tree_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED) * PAGE_SIZE);
> +	seq_printf(m, "file_dirty %lu\n",
> +		   tree_stat(memcg, MEM_CGROUP_STAT_DIRTY) * PAGE_SIZE);
> +	seq_printf(m, "file_writeback %lu\n",
> +		   tree_stat(memcg, MEM_CGROUP_STAT_WRITEBACK) * PAGE_SIZE);
> +
> +	/* Memory management events */
> +
> +	seq_printf(m, "pgfault %lu\n",
> +		   tree_events(memcg, MEM_CGROUP_EVENTS_PGFAULT));
> +	seq_printf(m, "pgmajfault %lu\n",
> +		   tree_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT));
> +
> +	return 0;
> +}