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Commit 5722d094 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

memcg, slab: cleanup memcg cache creation 



This patch cleans up the memcg cache creation path as follows:

- Move memcg cache name creation to a separate function to be called
  from kmem_cache_create_memcg().  This allows us to get rid of the mutex
  protecting the temporary buffer used for the name formatting, because
  the whole cache creation path is protected by the slab_mutex.

- Get rid of memcg_create_kmem_cache().  This function serves as a proxy
  to kmem_cache_create_memcg().  After separating the cache name creation
  path, it would be reduced to a function call, so let's inline it.

Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Glauber Costa <glommer@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a44cb944

include/linux/memcontrol.h

+9 −0
Original line number Diff line number Diff line
@@ -491,6 +491,9 @@ void __memcg_kmem_commit_charge(struct page *page, 
void __memcg_kmem_uncharge_pages(struct page *page, int order);



int memcg_cache_id(struct mem_cgroup *memcg);



char *memcg_create_cache_name(struct mem_cgroup *memcg,

			      struct kmem_cache *root_cache);

int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,

			     struct kmem_cache *root_cache);

void memcg_free_cache_params(struct kmem_cache *s);
@@ -635,6 +638,12 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg) 
	return -1;

}



static inline char *memcg_create_cache_name(struct mem_cgroup *memcg,

					    struct kmem_cache *root_cache)

{

	return NULL;

}



static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,

		struct kmem_cache *s, struct kmem_cache *root_cache)

{

mm/memcontrol.c

+39 −50
Original line number Diff line number Diff line
@@ -3094,6 +3094,29 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups) 
	return 0;

}



char *memcg_create_cache_name(struct mem_cgroup *memcg,

			      struct kmem_cache *root_cache)

{

	static char *buf = NULL;



	/*

	 * We need a mutex here to protect the shared buffer. Since this is

	 * expected to be called only on cache creation, we can employ the

	 * slab_mutex for that purpose.

	 */

	lockdep_assert_held(&slab_mutex);



	if (!buf) {

		buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);

		if (!buf)

			return NULL;

	}



	cgroup_name(memcg->css.cgroup, buf, NAME_MAX + 1);

	return kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,

			 memcg_cache_id(memcg), buf);

}



int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,

			     struct kmem_cache *root_cache)

{
@@ -3298,46 +3321,6 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep) 
	schedule_work(&cachep->memcg_params->destroy);

}



static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,

						  struct kmem_cache *s)

{

	struct kmem_cache *new = NULL;

	static char *tmp_path = NULL, *tmp_name = NULL;

	static DEFINE_MUTEX(mutex);	/* protects tmp_name */



	BUG_ON(!memcg_can_account_kmem(memcg));



	mutex_lock(&mutex);

	/*

	 * kmem_cache_create_memcg duplicates the given name and

	 * cgroup_name for this name requires RCU context.

	 * This static temporary buffer is used to prevent from

	 * pointless shortliving allocation.

	 */

	if (!tmp_path || !tmp_name) {

		if (!tmp_path)

			tmp_path = kmalloc(PATH_MAX, GFP_KERNEL);

		if (!tmp_name)

			tmp_name = kmalloc(NAME_MAX + 1, GFP_KERNEL);

		if (!tmp_path || !tmp_name)

			goto out;

	}



	cgroup_name(memcg->css.cgroup, tmp_name, NAME_MAX + 1);

	snprintf(tmp_path, PATH_MAX, "%s(%d:%s)", s->name,

		 memcg_cache_id(memcg), tmp_name);



	new = kmem_cache_create_memcg(memcg, tmp_path, s->object_size, s->align,

				      (s->flags & ~SLAB_PANIC), s->ctor, s);

	if (new)

		new->allocflags |= __GFP_KMEMCG;

	else

		new = s;

out:

	mutex_unlock(&mutex);

	return new;

}



void kmem_cache_destroy_memcg_children(struct kmem_cache *s)

{

	struct kmem_cache *c;
@@ -3384,12 +3367,6 @@ void kmem_cache_destroy_memcg_children(struct kmem_cache *s) 
	mutex_unlock(&activate_kmem_mutex);

}



struct create_work {

	struct mem_cgroup *memcg;

	struct kmem_cache *cachep;

	struct work_struct work;

};



static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)

{

	struct kmem_cache *cachep;
@@ -3407,13 +3384,25 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg) 
	mutex_unlock(&memcg->slab_caches_mutex);

}



struct create_work {

	struct mem_cgroup *memcg;

	struct kmem_cache *cachep;

	struct work_struct work;

};



static void memcg_create_cache_work_func(struct work_struct *w)

{

	struct create_work *cw;

	struct create_work *cw = container_of(w, struct create_work, work);

	struct mem_cgroup *memcg = cw->memcg;

	struct kmem_cache *cachep = cw->cachep;

	struct kmem_cache *new;



	cw = container_of(w, struct create_work, work);

	memcg_create_kmem_cache(cw->memcg, cw->cachep);

	css_put(&cw->memcg->css);

	new = kmem_cache_create_memcg(memcg, cachep->name,

			cachep->object_size, cachep->align,

			cachep->flags & ~SLAB_PANIC, cachep->ctor, cachep);

	if (new)

		new->allocflags |= __GFP_KMEMCG;

	css_put(&memcg->css);

	kfree(cw);

}

mm/slab_common.c

+4 −1
Original line number Diff line number Diff line
@@ -215,6 +215,9 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size, 
	s->align = calculate_alignment(flags, align, size);

	s->ctor = ctor;



	if (memcg)

		s->name = memcg_create_cache_name(memcg, parent_cache);

	else

		s->name = kstrdup(name, GFP_KERNEL);

	if (!s->name)

		goto out_free_cache;