Re: [v7 PATCH 05/12] mm: memcontrol: rename shrinker_map to shrinker_info

[Roman Gushchin <guro@fb.com>]

On Tue, Feb 09, 2021 at 03:33:56PM -0800, Yang Shi wrote:
> On Tue, Feb 9, 2021 at 12:50 PM Roman Gushchin <guro@fb.com> wrote:
> >
> > On Tue, Feb 09, 2021 at 09:46:39AM -0800, Yang Shi wrote:
> > > The following patch is going to add nr_deferred into shrinker_map, the change will
> > > make shrinker_map not only include map anymore, so rename it to "memcg_shrinker_info".
> > > And this should make the patch adding nr_deferred cleaner and readable and make
> > > review easier.  Also remove the "memcg_" prefix.
> > >
> > > Acked-by: Vlastimil Babka <vbabka@suse.cz>
> > > Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> > > Signed-off-by: Yang Shi <shy828301@gmail.com>
> > > ---
> > >  include/linux/memcontrol.h |  8 ++---
> > >  mm/memcontrol.c            |  6 ++--
> > >  mm/vmscan.c                | 62 +++++++++++++++++++-------------------
> > >  3 files changed, 38 insertions(+), 38 deletions(-)
> > >
> > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > > index 1739f17e0939..4c9253896e25 100644
> > > --- a/include/linux/memcontrol.h
> > > +++ b/include/linux/memcontrol.h
> > > @@ -96,7 +96,7 @@ struct lruvec_stat {
> > >   * Bitmap of shrinker::id corresponding to memcg-aware shrinkers,
> > >   * which have elements charged to this memcg.
> > >   */
> > > -struct memcg_shrinker_map {
> > > +struct shrinker_info {
> > >       struct rcu_head rcu;
> > >       unsigned long map[];
> > >  };
> > > @@ -118,7 +118,7 @@ struct mem_cgroup_per_node {
> > >
> > >       struct mem_cgroup_reclaim_iter  iter;
> > >
> > > -     struct memcg_shrinker_map __rcu *shrinker_map;
> > > +     struct shrinker_info __rcu      *shrinker_info;
> >
> > Nice!
> >
> > I really like how it looks now in comparison to the v1. Thank you for
> > working on it!
> 
> Thanks a lot for all the great comments from all of you.
> 
> >
> > >
> > >       struct rb_node          tree_node;      /* RB tree node */
> > >       unsigned long           usage_in_excess;/* Set to the value by which */
> > > @@ -1581,8 +1581,8 @@ static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
> > >       return false;
> > >  }
> > >
> > > -int alloc_shrinker_maps(struct mem_cgroup *memcg);
> > > -void free_shrinker_maps(struct mem_cgroup *memcg);
> > > +int alloc_shrinker_info(struct mem_cgroup *memcg);
> > > +void free_shrinker_info(struct mem_cgroup *memcg);
> > >  void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id);
> > >  #else
> > >  #define mem_cgroup_sockets_enabled 0
> > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > > index f5c9a0d2160b..f64ad0d044d9 100644
> > > --- a/mm/memcontrol.c
> > > +++ b/mm/memcontrol.c
> > > @@ -5246,11 +5246,11 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
> > >       struct mem_cgroup *memcg = mem_cgroup_from_css(css);
> > >
> > >       /*
> > > -      * A memcg must be visible for expand_shrinker_maps()
> > > +      * A memcg must be visible for expand_shrinker_info()
> > >        * by the time the maps are allocated. So, we allocate maps
> > >        * here, when for_each_mem_cgroup() can't skip it.
> > >        */
> > > -     if (alloc_shrinker_maps(memcg)) {
> > > +     if (alloc_shrinker_info(memcg)) {
> > >               mem_cgroup_id_remove(memcg);
> > >               return -ENOMEM;
> > >       }
> > > @@ -5314,7 +5314,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
> > >       vmpressure_cleanup(&memcg->vmpressure);
> > >       cancel_work_sync(&memcg->high_work);
> > >       mem_cgroup_remove_from_trees(memcg);
> > > -     free_shrinker_maps(memcg);
> > > +     free_shrinker_info(memcg);
> > >       memcg_free_kmem(memcg);
> > >       mem_cgroup_free(memcg);
> > >  }
> > > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > > index 641077b09e5d..9436f9246d32 100644
> > > --- a/mm/vmscan.c
> > > +++ b/mm/vmscan.c
> > > @@ -190,20 +190,20 @@ static int shrinker_nr_max;
> > >  #define NR_MAX_TO_SHR_MAP_SIZE(nr_max) \
> > >       (DIV_ROUND_UP(nr_max, BITS_PER_LONG) * sizeof(unsigned long))
> > >
> > > -static void free_shrinker_map_rcu(struct rcu_head *head)
> > > +static void free_shrinker_info_rcu(struct rcu_head *head)
> > >  {
> > > -     kvfree(container_of(head, struct memcg_shrinker_map, rcu));
> > > +     kvfree(container_of(head, struct shrinker_info, rcu));
> > >  }
> > >
> > > -static int expand_one_shrinker_map(struct mem_cgroup *memcg,
> > > +static int expand_one_shrinker_info(struct mem_cgroup *memcg,
> > >                                  int size, int old_size)
> > >  {
> > > -     struct memcg_shrinker_map *new, *old;
> > > +     struct shrinker_info *new, *old;
> > >       int nid;
> > >
> > >       for_each_node(nid) {
> > >               old = rcu_dereference_protected(
> > > -                     mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true);
> > > +                     mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, true);
> > >               /* Not yet online memcg */
> > >               if (!old)
> > >                       return 0;
> > > @@ -216,17 +216,17 @@ static int expand_one_shrinker_map(struct mem_cgroup *memcg,
> > >               memset(new->map, (int)0xff, old_size);
> > >               memset((void *)new->map + old_size, 0, size - old_size);
> > >
> > > -             rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new);
> > > -             call_rcu(&old->rcu, free_shrinker_map_rcu);
> > > +             rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, new);
> > > +             call_rcu(&old->rcu, free_shrinker_info_rcu);
> >
> > Why not use kvfree_rcu() and get rid of free_shrinker_info_rcu() callback?
> 
> Just because this patch is aimed to rename the structure. I think it
> may be more preferred to have the cleanup in a separate patch?

Completely up to you, I'm fine with either option.

Thanks!