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

[Muchun Song]

On Tue, Oct 27, 2020 at 9:36 PM Michal Hocko <mhocko@xxxxxxxx> wrote:
>
> 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.

If we want to avoid abuse of mem_cgroup_node_lruvec. We can move
those functions to the memcontrol.c. And add the "static" attribute to the
mem_cgroup_node_lruvec. Just export mem_cgroup_lruvec and
mem_cgroup_page_lruvec. Is this OK?

Thanks.

> --
> Michal Hocko
> SUSE Labs

-- 
Yours,
Muchun