linux-kernel - Re: [PATCH 2/2] mm: memcontrol: account pagetables per node

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Message-ID: <20201130201916.GB23216@cmpxchg.org>
Date:   Mon, 30 Nov 2020 15:19:16 -0500
From:   Johannes Weiner <hannes@...xchg.org>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     Roman Gushchin <guro@...com>, Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mm: memcontrol: account pagetables per node

On Wed, Nov 25, 2020 at 04:56:03PM -0800, Shakeel Butt wrote:
> For many workloads, pagetable consumption is significant and it makes
> sense to expose it in the memory.stat for the memory cgroups. However at
> the moment, the pagetables are accounted per-zone. Converting them to
> per-node and using the right interface will correctly account for the
> memory cgroups as well.
> 
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>

Agreed, this is a useful stat item to have.

Just one trivial issue:

> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -151,7 +151,6 @@ enum zone_stat_item {
>  	NR_ZONE_UNEVICTABLE,
>  	NR_ZONE_WRITE_PENDING,	/* Count of dirty, writeback and unstable pages */
>  	NR_MLOCK,		/* mlock()ed pages found and moved off LRU */
> -	NR_PAGETABLE,		/* used for pagetables */
>  	/* Second 128 byte cacheline */
>  	NR_BOUNCE,
>  #if IS_ENABLED(CONFIG_ZSMALLOC)
> @@ -206,6 +205,7 @@ enum node_stat_item {
>  #if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
>  	NR_KERNEL_SCS_KB,	/* measured in KiB */
>  #endif
> +	NR_PAGETABLE,		/* used for pagetables */
>  	NR_VM_NODE_STAT_ITEMS
>  };

You need to update mm/vmstat.c::vmstat_text accordingly or
/proc/vmstat output will be bogus.

With that fixed, please feel free to add:
Acked-by: Johannes Weiner <hannes@...xchg.org>