Re: [PATCH v2] memcg: reduce the size of struct memcg 244-fold.

[Greg Thelen <gthelen@google.com>]

On Thu, Jan 24 2013, Andrew Morton wrote:

> On Wed, 23 Jan 2013 23:50:31 -0800
> Greg Thelen <gthelen@google.com> wrote:
>
>> > --- a/mm/memcontrol.c
>> > +++ b/mm/memcontrol.c
>> > @@ -172,7 +172,7 @@ struct mem_cgroup_per_node {
>> >  };
>> >  
>> >  struct mem_cgroup_lru_info {
>> > -	struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
>> > +	struct mem_cgroup_per_node *nodeinfo[0];
>> 
>> It seems like a VM_BUG_ON() in mem_cgroup_zoneinfo() asserting that the
>> nid index is less than nr_node_ids would be good at catching illegal
>> indexes.  I don't see any illegal indexes in your patch, but I fear that
>> someday a MAX_NUMNODES based for() loop might sneak in.
>
> Can't hurt ;)
>
>> Tangential question: why use inline here?  I figure that modern
>> compilers are good at making inlining decisions.
>
> And that'll save some disk space.
>
> This?

Yup, that looks good to me.

Acked-by: Greg Thelen <gthelen@google.com>

> --- a/mm/memcontrol.c~memcg-reduce-the-size-of-struct-memcg-244-fold-fix
> +++ a/mm/memcontrol.c
> @@ -381,7 +381,7 @@ enum {
>  		((1 << KMEM_ACCOUNTED_ACTIVE) | (1 << KMEM_ACCOUNTED_ACTIVATED))
>  
>  #ifdef CONFIG_MEMCG_KMEM
> -static inline void memcg_kmem_set_active(struct mem_cgroup *memcg)
> +static void memcg_kmem_set_active(struct mem_cgroup *memcg)
>  {
>  	set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
>  }
> @@ -645,6 +645,7 @@ static void drain_all_stock_async(struct
>  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];
>  }
>  
> _
>
> Glauber, could you please cc me on patches more often?  It's a bit of a
> pita having to go back to the mailing list to see if there has been
> more dicussion and I may end up missing late review comments and acks.

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