Re: [PATCH] mm: memcontrol: drop superfluous entry in the per-memcg stats array

[Andrew Morton]

On Tue, 26 Jan 2016 15:55:29 -0500 Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> MEM_CGROUP_STAT_NSTATS is just a delimiter for cgroup1 statistics, not
> an actual array entry. Reuse it for the first cgroup2 stat entry, like
> in the event array.
> 
> ...
>
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -51,7 +51,7 @@ enum mem_cgroup_stat_index {
>  	MEM_CGROUP_STAT_SWAP,		/* # of pages, swapped out */
>  	MEM_CGROUP_STAT_NSTATS,
>  	/* default hierarchy stats */
> -	MEMCG_SOCK,
> +	MEMCG_SOCK = MEM_CGROUP_STAT_NSTATS,
>  	MEMCG_NR_STAT,
>  };

The code looks a bit odd.  How come mem_cgroup_stat_names[] ends with
"swap"?  Should MEMCG_SOCK be in there at all?

And the naming is a bit sad.  "MEM_CGROUP_STAT_FILE_MAPPED" maps to
"mapped_file", not "file_mapped".