Re: [PATCH 5/5] mm: memcontrol: Simplify the mem_cgroup_page_lruvec

[Michal Hocko]

On Tue 27-10-20 16:02:56, Muchun Song wrote:
> We can reuse the code of mem_cgroup_lruvec() to simplify the code
> of the mem_cgroup_page_lruvec().

yes, removing the code duplication is reasonable. But ...

> 
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
>  include/linux/memcontrol.h | 44 +++++++++++++++++++++++++++-----------
>  mm/memcontrol.c            | 40 ----------------------------------
>  2 files changed, 32 insertions(+), 52 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 95807bf6be64..5e8480e54cd8 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -451,16 +451,9 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
>  	return memcg->nodeinfo[nid];
>  }
>  
> -/**
> - * mem_cgroup_lruvec - get the lru list vector for a memcg & node
> - * @memcg: memcg of the wanted lruvec
> - *
> - * Returns the lru list vector holding pages for a given @memcg &
> - * @node combination. This can be the node lruvec, if the memory
> - * controller is disabled.
> - */
> -static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
> -					       struct pglist_data *pgdat)
> +static inline struct lruvec *mem_cgroup_node_lruvec(struct mem_cgroup *memcg,
> +						    struct pglist_data *pgdat,
> +						    int nid)

This is just wrong interface. Either take nid or pgdat. You do not want
both because that just begs for wrong usage.
-- 
Michal Hocko
SUSE Labs