On Fri, 25 May 2012, Glauber Costa wrote:
> index dacd1fb..4689034 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -467,6 +467,23 @@ struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
> EXPORT_SYMBOL(tcp_proto_cgroup);
> #endif /* CONFIG_INET */
>
> +char *mem_cgroup_cache_name(struct mem_cgroup *memcg, struct kmem_cache *cachep)
> +{
> + char *name;
> + struct dentry *dentry;
> +
> + rcu_read_lock();
> + dentry = rcu_dereference(memcg->css.cgroup->dentry);
> + rcu_read_unlock();
> +
> + BUG_ON(dentry == NULL);
> +
> + name = kasprintf(GFP_KERNEL, "%s(%d:%s)",
> + cachep->name, css_id(&memcg->css), dentry->d_name.name);
> +
> + return name;
> +}
Function allocates a string that is supposed to be disposed of by the
caller. That needs to be documented and maybe even the name needs to
reflect that.
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -4002,6 +4002,38 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
> }
> EXPORT_SYMBOL(kmem_cache_create);
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
> + struct kmem_cache *s)
> +{
> + char *name;
> + struct kmem_cache *new;
> +
> + name = mem_cgroup_cache_name(memcg, s);
> + if (!name)
> + return NULL;
> +
> + new = kmem_cache_create_memcg(memcg, name, s->objsize, s->align,
> + (s->allocflags & ~SLAB_PANIC), s->ctor);
Hmmm... A full duplicate of the slab cache? We may have many sparsely
used portions of the per node and per cpu structure as a result.
> + * prevent it from being deleted. If kmem_cache_destroy() is
> + * called for the root cache before we call it for a child cache,
> + * it will be queued for destruction when we finally drop the
> + * reference on the child cache.
> + */
> + if (new) {
> + down_write(&slub_lock);
> + s->refcount++;
> + up_write(&slub_lock);
> + }
Why do you need to increase the refcount? You made a full copy right?
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