Re: [PATCH 4/8] mm: memcontrol: group kmem init and exit functions together

[Michal Hocko]

On Tue 08-12-15 13:34:21, Johannes Weiner wrote:
> Put all the related code to setup and teardown the kmem accounting
> state into the same location. No functional change intended.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
>  mm/memcontrol.c | 157 +++++++++++++++++++++++++++-----------------------------
>  1 file changed, 76 insertions(+), 81 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 22b8c4f..5118618 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2924,12 +2924,88 @@ static int memcg_propagate_kmem(struct mem_cgroup *memcg)
>  	mutex_unlock(&memcg_limit_mutex);
>  	return ret;
>  }
> +
> +static int memcg_init_kmem(struct mem_cgroup *memcg)
> +{
> +	int ret;
> +
> +	ret = memcg_propagate_kmem(memcg);
> +	if (ret)
> +		return ret;
> +
> +	return tcp_init_cgroup(memcg);
> +}
> +
> +static void memcg_offline_kmem(struct mem_cgroup *memcg)
> +{
> +	struct cgroup_subsys_state *css;
> +	struct mem_cgroup *parent, *child;
> +	int kmemcg_id;
> +
> +	if (memcg->kmem_state != KMEM_ONLINE)
> +		return;
> +	/*
> +	 * Clear the online state before clearing memcg_caches array
> +	 * entries. The slab_mutex in memcg_deactivate_kmem_caches()
> +	 * guarantees that no cache will be created for this cgroup
> +	 * after we are done (see memcg_create_kmem_cache()).
> +	 */
> +	memcg->kmem_state = KMEM_ALLOCATED;
> +
> +	memcg_deactivate_kmem_caches(memcg);
> +
> +	kmemcg_id = memcg->kmemcg_id;
> +	BUG_ON(kmemcg_id < 0);
> +
> +	parent = parent_mem_cgroup(memcg);
> +	if (!parent)
> +		parent = root_mem_cgroup;
> +
> +	/*
> +	 * Change kmemcg_id of this cgroup and all its descendants to the
> +	 * parent's id, and then move all entries from this cgroup's list_lrus
> +	 * to ones of the parent. After we have finished, all list_lrus
> +	 * corresponding to this cgroup are guaranteed to remain empty. The
> +	 * ordering is imposed by list_lru_node->lock taken by
> +	 * memcg_drain_all_list_lrus().
> +	 */
> +	css_for_each_descendant_pre(css, &memcg->css) {
> +		child = mem_cgroup_from_css(css);
> +		BUG_ON(child->kmemcg_id != kmemcg_id);
> +		child->kmemcg_id = parent->kmemcg_id;
> +		if (!memcg->use_hierarchy)
> +			break;
> +	}
> +	memcg_drain_all_list_lrus(kmemcg_id, parent->kmemcg_id);
> +
> +	memcg_free_cache_id(kmemcg_id);
> +}
> +
> +static void memcg_free_kmem(struct mem_cgroup *memcg)
> +{
> +	if (memcg->kmem_state == KMEM_ALLOCATED) {
> +		memcg_destroy_kmem_caches(memcg);
> +		static_branch_dec(&memcg_kmem_enabled_key);
> +		WARN_ON(page_counter_read(&memcg->kmem));
> +	}
> +	tcp_destroy_cgroup(memcg);
> +}
>  #else
>  static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
>  				   unsigned long limit)
>  {
>  	return -EINVAL;
>  }
> +static int memcg_init_kmem(struct mem_cgroup *memcg)
> +{
> +	return 0;
> +}
> +static void memcg_offline_kmem(struct mem_cgroup *memcg)
> +{
> +}
> +static void memcg_free_kmem(struct mem_cgroup *memcg)
> +{
> +}
>  #endif /* CONFIG_MEMCG_KMEM */
>  
>  /*
> @@ -3555,87 +3631,6 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
>  	return 0;
>  }
>  
> -#ifdef CONFIG_MEMCG_KMEM
> -static int memcg_init_kmem(struct mem_cgroup *memcg)
> -{
> -	int ret;
> -
> -	ret = memcg_propagate_kmem(memcg);
> -	if (ret)
> -		return ret;
> -
> -	return tcp_init_cgroup(memcg);
> -}
> -
> -static void memcg_offline_kmem(struct mem_cgroup *memcg)
> -{
> -	struct cgroup_subsys_state *css;
> -	struct mem_cgroup *parent, *child;
> -	int kmemcg_id;
> -
> -	if (memcg->kmem_state != KMEM_ONLINE)
> -		return;
> -	/*
> -	 * Clear the online state before clearing memcg_caches array
> -	 * entries. The slab_mutex in memcg_deactivate_kmem_caches()
> -	 * guarantees that no cache will be created for this cgroup
> -	 * after we are done (see memcg_create_kmem_cache()).
> -	 */
> -	memcg->kmem_state = KMEM_ALLOCATED;
> -
> -	memcg_deactivate_kmem_caches(memcg);
> -
> -	kmemcg_id = memcg->kmemcg_id;
> -	BUG_ON(kmemcg_id < 0);
> -
> -	parent = parent_mem_cgroup(memcg);
> -	if (!parent)
> -		parent = root_mem_cgroup;
> -
> -	/*
> -	 * Change kmemcg_id of this cgroup and all its descendants to the
> -	 * parent's id, and then move all entries from this cgroup's list_lrus
> -	 * to ones of the parent. After we have finished, all list_lrus
> -	 * corresponding to this cgroup are guaranteed to remain empty. The
> -	 * ordering is imposed by list_lru_node->lock taken by
> -	 * memcg_drain_all_list_lrus().
> -	 */
> -	css_for_each_descendant_pre(css, &memcg->css) {
> -		child = mem_cgroup_from_css(css);
> -		BUG_ON(child->kmemcg_id != kmemcg_id);
> -		child->kmemcg_id = parent->kmemcg_id;
> -		if (!memcg->use_hierarchy)
> -			break;
> -	}
> -	memcg_drain_all_list_lrus(kmemcg_id, parent->kmemcg_id);
> -
> -	memcg_free_cache_id(kmemcg_id);
> -}
> -
> -static void memcg_free_kmem(struct mem_cgroup *memcg)
> -{
> -	if (memcg->kmem_state == KMEM_ALLOCATED) {
> -		memcg_destroy_kmem_caches(memcg);
> -		static_branch_dec(&memcg_kmem_enabled_key);
> -		WARN_ON(page_counter_read(&memcg->kmem));
> -	}
> -	tcp_destroy_cgroup(memcg);
> -}
> -#else
> -static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
> -{
> -	return 0;
> -}
> -
> -static void memcg_offline_kmem(struct mem_cgroup *memcg)
> -{
> -}
> -
> -static void memcg_free_kmem(struct mem_cgroup *memcg)
> -{
> -}
> -#endif
> -
>  #ifdef CONFIG_CGROUP_WRITEBACK
>  
>  struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg)
> -- 
> 2.6.3

-- 
Michal Hocko
SUSE Labs
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