Re: [PATCH -mm v2] memcg: cleanup kmem cache creation/destruction functions naming

[Michal Hocko]

On Tue 13-05-14 19:05:51, Vladimir Davydov wrote:
> Current names are rather inconsistent. Let's try to improve them.
> 
> Brief change log:
> 
> ** old name **                          ** new name **
> 
> kmem_cache_create_memcg                 memcg_create_kmem_cache
> memcg_kmem_create_cache                 memcg_regsiter_cache
> memcg_kmem_destroy_cache                memcg_unregister_cache
> 
> kmem_cache_destroy_memcg_children       memcg_cleanup_cache_params
> mem_cgroup_destroy_all_caches           memcg_unregister_all_caches
> 
> create_work                             memcg_register_cache_work
> memcg_create_cache_work_func            memcg_register_cache_func
> memcg_create_cache_enqueue              memcg_schedule_register_cache
> 
> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxx>
Thanks!

> ---
>  include/linux/memcontrol.h |    2 +-
>  include/linux/slab.h       |    2 +-
>  mm/memcontrol.c            |   60 +++++++++++++++++++++-----------------------
>  mm/slab_common.c           |   12 ++++-----
>  4 files changed, 36 insertions(+), 40 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index aa429de275cc..c3a53cbb88eb 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -514,7 +514,7 @@ __memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
>  int __memcg_charge_slab(struct kmem_cache *cachep, gfp_t gfp, int order);
>  void __memcg_uncharge_slab(struct kmem_cache *cachep, int order);
>  
> -int __kmem_cache_destroy_memcg_children(struct kmem_cache *s);
> +int __memcg_cleanup_cache_params(struct kmem_cache *s);
>  
>  /**
>   * memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 86e5b26fbdab..1d9abb7d22a0 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -116,7 +116,7 @@ struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
>  			unsigned long,
>  			void (*)(void *));
>  #ifdef CONFIG_MEMCG_KMEM
> -struct kmem_cache *kmem_cache_create_memcg(struct mem_cgroup *,
> +struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *,
>  					   struct kmem_cache *,
>  					   const char *);
>  #endif
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index f5ea266f4d9a..b12a05049f2a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3127,8 +3127,8 @@ void memcg_free_cache_params(struct kmem_cache *s)
>  	kfree(s->memcg_params);
>  }
>  
> -static void memcg_kmem_create_cache(struct mem_cgroup *memcg,
> -				    struct kmem_cache *root_cache)
> +static void memcg_register_cache(struct mem_cgroup *memcg,
> +				 struct kmem_cache *root_cache)
>  {
>  	static char memcg_name_buf[NAME_MAX + 1]; /* protected by
>  						     memcg_slab_mutex */
> @@ -3148,7 +3148,7 @@ static void memcg_kmem_create_cache(struct mem_cgroup *memcg,
>  		return;
>  
>  	cgroup_name(memcg->css.cgroup, memcg_name_buf, NAME_MAX + 1);
> -	cachep = kmem_cache_create_memcg(memcg, root_cache, memcg_name_buf);
> +	cachep = memcg_create_kmem_cache(memcg, root_cache, memcg_name_buf);
>  	/*
>  	 * If we could not create a memcg cache, do not complain, because
>  	 * that's not critical at all as we can always proceed with the root
> @@ -3170,7 +3170,7 @@ static void memcg_kmem_create_cache(struct mem_cgroup *memcg,
>  	root_cache->memcg_params->memcg_caches[id] = cachep;
>  }
>  
> -static void memcg_kmem_destroy_cache(struct kmem_cache *cachep)
> +static void memcg_unregister_cache(struct kmem_cache *cachep)
>  {
>  	struct kmem_cache *root_cache;
>  	struct mem_cgroup *memcg;
> @@ -3223,7 +3223,7 @@ static inline void memcg_resume_kmem_account(void)
>  	current->memcg_kmem_skip_account--;
>  }
>  
> -int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
> +int __memcg_cleanup_cache_params(struct kmem_cache *s)
>  {
>  	struct kmem_cache *c;
>  	int i, failed = 0;
> @@ -3234,7 +3234,7 @@ int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
>  		if (!c)
>  			continue;
>  
> -		memcg_kmem_destroy_cache(c);
> +		memcg_unregister_cache(c);
>  
>  		if (cache_from_memcg_idx(s, i))
>  			failed++;
> @@ -3243,7 +3243,7 @@ int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
>  	return failed;
>  }
>  
> -static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
> +static void memcg_unregister_all_caches(struct mem_cgroup *memcg)
>  {
>  	struct kmem_cache *cachep;
>  	struct memcg_cache_params *params, *tmp;
> @@ -3256,25 +3256,26 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
>  		cachep = memcg_params_to_cache(params);
>  		kmem_cache_shrink(cachep);
>  		if (atomic_read(&cachep->memcg_params->nr_pages) == 0)
> -			memcg_kmem_destroy_cache(cachep);
> +			memcg_unregister_cache(cachep);
>  	}
>  	mutex_unlock(&memcg_slab_mutex);
>  }
>  
> -struct create_work {
> +struct memcg_register_cache_work {
>  	struct mem_cgroup *memcg;
>  	struct kmem_cache *cachep;
>  	struct work_struct work;
>  };
>  
> -static void memcg_create_cache_work_func(struct work_struct *w)
> +static void memcg_register_cache_func(struct work_struct *w)
>  {
> -	struct create_work *cw = container_of(w, struct create_work, work);
> +	struct memcg_register_cache_work *cw =
> +		container_of(w, struct memcg_register_cache_work, work);
>  	struct mem_cgroup *memcg = cw->memcg;
>  	struct kmem_cache *cachep = cw->cachep;
>  
>  	mutex_lock(&memcg_slab_mutex);
> -	memcg_kmem_create_cache(memcg, cachep);
> +	memcg_register_cache(memcg, cachep);
>  	mutex_unlock(&memcg_slab_mutex);
>  
>  	css_put(&memcg->css);
> @@ -3284,12 +3285,12 @@ static void memcg_create_cache_work_func(struct work_struct *w)
>  /*
>   * Enqueue the creation of a per-memcg kmem_cache.
>   */
> -static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
> -					 struct kmem_cache *cachep)
> +static void __memcg_schedule_register_cache(struct mem_cgroup *memcg,
> +					    struct kmem_cache *cachep)
>  {
> -	struct create_work *cw;
> +	struct memcg_register_cache_work *cw;
>  
> -	cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
> +	cw = kmalloc(sizeof(*cw), GFP_NOWAIT);
>  	if (cw == NULL) {
>  		css_put(&memcg->css);
>  		return;
> @@ -3298,17 +3299,17 @@ static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
>  	cw->memcg = memcg;
>  	cw->cachep = cachep;
>  
> -	INIT_WORK(&cw->work, memcg_create_cache_work_func);
> +	INIT_WORK(&cw->work, memcg_register_cache_func);
>  	schedule_work(&cw->work);
>  }
>  
> -static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
> -				       struct kmem_cache *cachep)
> +static void memcg_schedule_register_cache(struct mem_cgroup *memcg,
> +					  struct kmem_cache *cachep)
>  {
>  	/*
>  	 * We need to stop accounting when we kmalloc, because if the
>  	 * corresponding kmalloc cache is not yet created, the first allocation
> -	 * in __memcg_create_cache_enqueue will recurse.
> +	 * in __memcg_schedule_register_cache will recurse.
>  	 *
>  	 * However, it is better to enclose the whole function. Depending on
>  	 * the debugging options enabled, INIT_WORK(), for instance, can
> @@ -3317,7 +3318,7 @@ static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
>  	 * the safest choice is to do it like this, wrapping the whole function.
>  	 */
>  	memcg_stop_kmem_account();
> -	__memcg_create_cache_enqueue(memcg, cachep);
> +	__memcg_schedule_register_cache(memcg, cachep);
>  	memcg_resume_kmem_account();
>  }
>  
> @@ -3388,16 +3389,11 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
>  	 *
>  	 * However, there are some clashes that can arrive from locking.
>  	 * For instance, because we acquire the slab_mutex while doing
> -	 * kmem_cache_dup, this means no further allocation could happen
> -	 * with the slab_mutex held.
> -	 *
> -	 * Also, because cache creation issue get_online_cpus(), this
> -	 * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
> -	 * that ends up reversed during cpu hotplug. (cpuset allocates
> -	 * a bunch of GFP_KERNEL memory during cpuup). Due to all that,
> -	 * better to defer everything.
> +	 * memcg_create_kmem_cache, this means no further allocation
> +	 * could happen with the slab_mutex held. So it's better to
> +	 * defer everything.
>  	 */
> -	memcg_create_cache_enqueue(memcg, cachep);
> +	memcg_schedule_register_cache(memcg, cachep);
>  	return cachep;
>  out:
>  	rcu_read_unlock();
> @@ -3521,7 +3517,7 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order)
>  	memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
>  }
>  #else
> -static inline void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
> +static inline void memcg_unregister_all_caches(struct mem_cgroup *memcg)
>  {
>  }
>  #endif /* CONFIG_MEMCG_KMEM */
> @@ -6399,7 +6395,7 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
>  	css_for_each_descendant_post(iter, css)
>  		mem_cgroup_reparent_charges(mem_cgroup_from_css(iter));
>  
> -	mem_cgroup_destroy_all_caches(memcg);
> +	memcg_unregister_all_caches(memcg);
>  	vmpressure_cleanup(&memcg->vmpressure);
>  }
>  
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 32175617cb75..48fafb61f35e 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -261,7 +261,7 @@ EXPORT_SYMBOL(kmem_cache_create);
>  
>  #ifdef CONFIG_MEMCG_KMEM
>  /*
> - * kmem_cache_create_memcg - Create a cache for a memory cgroup.
> + * memcg_create_kmem_cache - Create a cache for a memory cgroup.
>   * @memcg: The memory cgroup the new cache is for.
>   * @root_cache: The parent of the new cache.
>   * @memcg_name: The name of the memory cgroup (used for naming the new cache).
> @@ -270,7 +270,7 @@ EXPORT_SYMBOL(kmem_cache_create);
>   * requests going from @memcg to @root_cache. The new cache inherits properties
>   * from its parent.
>   */
> -struct kmem_cache *kmem_cache_create_memcg(struct mem_cgroup *memcg,
> +struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
>  					   struct kmem_cache *root_cache,
>  					   const char *memcg_name)
>  {
> @@ -305,7 +305,7 @@ out_unlock:
>  	return s;
>  }
>  
> -static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
> +static int memcg_cleanup_cache_params(struct kmem_cache *s)
>  {
>  	int rc;
>  
> @@ -314,13 +314,13 @@ static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
>  		return 0;
>  
>  	mutex_unlock(&slab_mutex);
> -	rc = __kmem_cache_destroy_memcg_children(s);
> +	rc = __memcg_cleanup_cache_params(s);
>  	mutex_lock(&slab_mutex);
>  
>  	return rc;
>  }
>  #else
> -static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
> +static int memcg_cleanup_cache_params(struct kmem_cache *s)
>  {
>  	return 0;
>  }
> @@ -343,7 +343,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
>  	if (s->refcount)
>  		goto out_unlock;
>  
> -	if (kmem_cache_destroy_memcg_children(s) != 0)
> +	if (memcg_cleanup_cache_params(s) != 0)
>  		goto out_unlock;
>  
>  	list_del(&s->list);
> -- 
> 1.7.10.4
> 

-- 
Michal Hocko
SUSE Labs
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