linux-kernel - Re: [PATCH] mm: rmap: fix huge file mmap accounting in the memcg stats

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Date:   Tue, 28 Mar 2017 16:52:46 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Vladimir Davydov <vdavydov.dev@...il.com>, linux-mm@...ck.org,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com
Subject: Re: [PATCH] mm: rmap: fix huge file mmap accounting in the memcg
 stats

On Tue 21-03-17 20:51:11, Johannes Weiner wrote:
> Huge pages are accounted as single units in the memcg's "file_mapped"
> counter. Account the correct number of base pages, like we do in the
> corresponding node counter.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

with the CC: stable 
Acked-by: Michal Hocko <mhocko@...e.com>

thanks!
> ---
>  include/linux/memcontrol.h | 6 ++++++
>  mm/rmap.c                  | 4 ++--
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index baa274150210..c5ebb32fef49 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -741,6 +741,12 @@ static inline bool mem_cgroup_oom_synchronize(bool wait)
>  	return false;
>  }
>  
> +static inline void mem_cgroup_update_page_stat(struct page *page,
> +					       enum mem_cgroup_stat_index idx,
> +					       int nr)
> +{
> +}
> +
>  static inline void mem_cgroup_inc_page_stat(struct page *page,
>  					    enum mem_cgroup_stat_index idx)
>  {
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 1d82057144ba..f514cdd84482 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1154,7 +1154,7 @@ void page_add_file_rmap(struct page *page, bool compound)
>  			goto out;
>  	}
>  	__mod_node_page_state(page_pgdat(page), NR_FILE_MAPPED, nr);
> -	mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
> +	mem_cgroup_update_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED, nr);
>  out:
>  	unlock_page_memcg(page);
>  }
> @@ -1194,7 +1194,7 @@ static void page_remove_file_rmap(struct page *page, bool compound)
>  	 * pte lock(a spinlock) is held, which implies preemption disabled.
>  	 */
>  	__mod_node_page_state(page_pgdat(page), NR_FILE_MAPPED, -nr);
> -	mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
> +	mem_cgroup_update_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED, -nr);
>  
>  	if (unlikely(PageMlocked(page)))
>  		clear_page_mlock(page);
> -- 
> 2.12.0
> 

-- 
Michal Hocko
SUSE Labs