linux-kernel - Re: [PATCH] memcg: writeback: use memcg->cgwb

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Message-ID: <20180421235057.iyl4sipppfx3qp3m@quack2.suse.cz>
Date:   Sun, 22 Apr 2018 01:50:57 +0200
From:   Jan Kara <jack@...e.cz>
To:     Wang Long <wanglong19@...tuan.com>
Cc:     hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
        aryabinin@...tuozzo.com, akpm@...ux-foundation.org,
        khlebnikov@...dex-team.ru, xboe@...nel.dk, jack@...e.cz,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        gthelen@...gle.com, tj@...nel.org
Subject: Re: [PATCH] memcg: writeback: use memcg->cgwb_list directly

On Sat 21-04-18 21:29:41, Wang Long wrote:
> Signed-off-by: Wang Long <wanglong19@...tuan.com>

Yeah, looks good. I guess it was originally intended to avoid compilation
errors if CONFIG_CGROUP_WRITEBACK was disabled. But it doesn't seem likely
we'll ever need that list outside of code under CONFIG_CGROUP_WRITEBACK. So
you can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  include/linux/memcontrol.h | 1 -
>  mm/backing-dev.c           | 4 ++--
>  mm/memcontrol.c            | 5 -----
>  3 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d99b71b..c0056e0 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1093,7 +1093,6 @@ static inline void dec_lruvec_page_state(struct page *page,
>  
>  #ifdef CONFIG_CGROUP_WRITEBACK
>  
> -struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg);
>  struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
>  void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
>  			 unsigned long *pheadroom, unsigned long *pdirty,
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 023190c..0a48e05 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -555,7 +555,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
>  	memcg = mem_cgroup_from_css(memcg_css);
>  	blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
>  	blkcg = css_to_blkcg(blkcg_css);
> -	memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
> +	memcg_cgwb_list = &memcg->cgwb_list;
>  	blkcg_cgwb_list = &blkcg->cgwb_list;
>  
>  	/* look up again under lock and discard on blkcg mismatch */
> @@ -734,7 +734,7 @@ static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
>   */
>  void wb_memcg_offline(struct mem_cgroup *memcg)
>  {
> -	struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
> +	struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
>  	struct bdi_writeback *wb, *next;
>  
>  	spin_lock_irq(&cgwb_lock);
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e074f7c..d1adb9c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3562,11 +3562,6 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
>  
>  #ifdef CONFIG_CGROUP_WRITEBACK
>  
> -struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg)
> -{
> -	return &memcg->cgwb_list;
> -}
> -
>  static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
>  {
>  	return wb_domain_init(&memcg->cgwb_domain, gfp);
> -- 
> 1.8.3.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR