Re: [PATCH v6 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state()

Shakeel Butt
2020-06-17T02:59:55Z

On Tue, Jun 16, 2020 at 7:50 PM Roman Gushchin <guro@fb.com> wrote:
>
> On Tue, Jun 16, 2020 at 06:52:09PM -0700, Shakeel Butt wrote:
> > On Mon, Jun 8, 2020 at 4:07 PM Roman Gushchin <guro@fb.com> wrote:
> > >
> > > To convert memcg and lruvec slab counters to bytes there must be
> > > a way to change these counters without touching node counters.
> > > Factor out __mod_memcg_lruvec_state() out of __mod_lruvec_state().
> > >
> > > Signed-off-by: Roman Gushchin <guro@fb.com>
> > > Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> > > Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
> > > ---
> > > include/linux/memcontrol.h | 17 +++++++++++++++
> > > mm/memcontrol.c | 43 +++++++++++++++++++++-----------------
> > > 2 files changed, 41 insertions(+), 19 deletions(-)
> > >
> > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > > index bbf624a7f5a6..93dbc7f9d8b8 100644
> > > --- a/include/linux/memcontrol.h
> > > +++ b/include/linux/memcontrol.h
> > > @@ -679,11 +679,23 @@ static inline unsigned long lruvec_page_state_local(struct lruvec *lruvec,
> > > return x;
> > > }
> > >
> > > +void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
> > > + int val);
> > > void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
> > > int val);
> > > void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val);
> > > void mod_memcg_obj_state(void *p, int idx, int val);
> > >
> > > +static inline void mod_memcg_lruvec_state(struct lruvec *lruvec,
> > > + enum node_stat_item idx, int val)
> >
> > Is this function used in later patches? Any benefit introducing it
> > here instead of in the patch where it is used for the first time?
>
> Yes, it's used in "mm: memcg/slab: charge individual slab objects instead of pages".
>
> It's a fairly large patchset with many internal dependencies, so there is
> always a trade-off between putting everything into a single patch, which is
> hard to review, and splitting out some changes, which make not much sense
> without seeing the whole picture.
>
> In this particular case splitting out a formal and easy-to-verify change makes
> the actual non-trivial patch smaller and hopefully easier for a review.
>
> But of course it's all subjective.
>
> Thanks!

I am fine with that.

Reviewed-by: Shakeel Butt <shakeelb@google.com>