On Tue 05-02-13 13:53:24, Johannes Weiner wrote:
[...]
> Subject: [patch] memcg: reduce the size of struct memcg 244-fold morrr fix
>
> Remove struct mem_cgroup_lru_info. It only holds the nodeinfo array
> and is actively misleading because there is all kinds of per-node
> stuff in addition to the LRU info in there. On that note, remove the
> incorrect comment as well.
>
> Move comment about the nodeinfo[0] array having to be the last field
> in struct mem_cgroup after said array. Should be more visible when
> attempting to append new members to the struct.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Yes, I like this. The info level is just artificatial and without any
good reason.
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Thanks
> ---
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 2382fe9..29cb9e9 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -179,10 +179,6 @@ struct mem_cgroup_per_node {
> struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
> };
>
> -struct mem_cgroup_lru_info {
> - struct mem_cgroup_per_node *nodeinfo[0];
> -};
> -
> /*
> * Cgroups above their limits are maintained in a RB-Tree, independent of
> * their hierarchy representation
> @@ -370,14 +366,8 @@ struct mem_cgroup {
> atomic_t numainfo_events;
> atomic_t numainfo_updating;
> #endif
> - /*
> - * Per cgroup active and inactive list, similar to the
> - * per zone LRU lists.
> - *
> - * WARNING: This has to be the last element of the struct. Don't
> - * add new fields after this point.
> - */
> - struct mem_cgroup_lru_info info;
> + struct mem_cgroup_per_node *nodeinfo[0];
> + /* WARNING: nodeinfo has to be the last member in here */
> };
>
> static inline size_t memcg_size(void)
> @@ -718,7 +708,7 @@ static struct mem_cgroup_per_zone *
> mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
> {
> VM_BUG_ON((unsigned)nid >= nr_node_ids);
> - return &memcg->info.nodeinfo[nid]->zoneinfo[zid];
> + return &memcg->nodeinfo[nid]->zoneinfo[zid];
> }
>
> struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
> @@ -6093,13 +6083,13 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
> mz->on_tree = false;
> mz->memcg = memcg;
> }
> - memcg->info.nodeinfo[node] = pn;
> + memcg->nodeinfo[node] = pn;
> return 0;
> }
>
> static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
> {
> - kfree(memcg->info.nodeinfo[node]);
> + kfree(memcg->nodeinfo[node]);
> }
>
> static struct mem_cgroup *mem_cgroup_alloc(void)
>
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--
Michal Hocko
SUSE Labs
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