Commit f3bb3043 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

memcg: don't call memcg_update_all_caches if new cache id fits 



memcg_update_all_caches grows arrays of per-memcg caches, so we only need
to call it when memcg_limited_groups_array_size is increased.  However,
currently we invoke it each time a new kmem-active memory cgroup is
created.  Then it just iterates over all slab_caches and does nothing
(memcg_update_cache_size returns immediately).

This patch fixes this insanity.  In the meantime it moves the code dealing
with id allocations to separate functions, memcg_alloc_cache_id and
memcg_free_cache_id.

Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 33a690c4

mm/memcontrol.c

+72 −64
Original line number Diff line number Diff line
@@ -649,11 +649,13 @@ int memcg_limited_groups_array_size; 
struct static_key memcg_kmem_enabled_key;

EXPORT_SYMBOL(memcg_kmem_enabled_key);



static void memcg_free_cache_id(int id);



static void disarm_kmem_keys(struct mem_cgroup *memcg)

{

	if (memcg_kmem_is_active(memcg)) {

		static_key_slow_dec(&memcg_kmem_enabled_key);

		ida_simple_remove(&kmem_limited_groups, memcg->kmemcg_id);

		memcg_free_cache_id(memcg->kmemcg_id);

	}

	/*

	 * This check can't live in kmem destruction function,
@@ -2906,19 +2908,44 @@ int memcg_cache_id(struct mem_cgroup *memcg) 
	return memcg ? memcg->kmemcg_id : -1;

}



static size_t memcg_caches_array_size(int num_groups)

static int memcg_alloc_cache_id(void)

{

	ssize_t size;

	if (num_groups <= 0)

		return 0;

	int id, size;

	int err;



	id = ida_simple_get(&kmem_limited_groups,

			    0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);

	if (id < 0)

		return id;



	if (id < memcg_limited_groups_array_size)

		return id;



	/*

	 * There's no space for the new id in memcg_caches arrays,

	 * so we have to grow them.

	 */



	size = 2 * num_groups;

	size = 2 * (id + 1);

	if (size < MEMCG_CACHES_MIN_SIZE)

		size = MEMCG_CACHES_MIN_SIZE;

	else if (size > MEMCG_CACHES_MAX_SIZE)

		size = MEMCG_CACHES_MAX_SIZE;



	return size;

	mutex_lock(&memcg_slab_mutex);

	err = memcg_update_all_caches(size);

	mutex_unlock(&memcg_slab_mutex);



	if (err) {

		ida_simple_remove(&kmem_limited_groups, id);

		return err;

	}

	return id;

}



static void memcg_free_cache_id(int id)

{

	ida_simple_remove(&kmem_limited_groups, id);

}



/*
@@ -2928,22 +2955,19 @@ static size_t memcg_caches_array_size(int num_groups) 
 */

void memcg_update_array_size(int num)

{

	if (num > memcg_limited_groups_array_size)

		memcg_limited_groups_array_size = memcg_caches_array_size(num);

	memcg_limited_groups_array_size = num;

}



int memcg_update_cache_size(struct kmem_cache *s, int num_groups)

{

	struct memcg_cache_params *cur_params = s->memcg_params;

	struct memcg_cache_params *new_params;

	size_t size;

	int i;



	VM_BUG_ON(!is_root_cache(s));



	if (num_groups > memcg_limited_groups_array_size) {

		int i;

		struct memcg_cache_params *new_params;

		ssize_t size = memcg_caches_array_size(num_groups);



		size *= sizeof(void *);

	size = num_groups * sizeof(void *);

	size += offsetof(struct memcg_cache_params, memcg_caches);



	new_params = kzalloc(size, GFP_KERNEL);
@@ -2980,7 +3004,6 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups) 
	rcu_assign_pointer(s->memcg_params, new_params);

	if (cur_params)

		kfree_rcu(cur_params, rcu_head);

	}

	return 0;

}
@@ -4181,23 +4204,12 @@ static int __memcg_activate_kmem(struct mem_cgroup *memcg, 
	if (err)

		goto out;



	memcg_id = ida_simple_get(&kmem_limited_groups,

				  0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);

	memcg_id = memcg_alloc_cache_id();

	if (memcg_id < 0) {

		err = memcg_id;

		goto out;

	}



	/*

	 * Make sure we have enough space for this cgroup in each root cache's

	 * memcg_params.

	 */

	mutex_lock(&memcg_slab_mutex);

	err = memcg_update_all_caches(memcg_id + 1);

	mutex_unlock(&memcg_slab_mutex);

	if (err)

		goto out_rmid;



	memcg->kmemcg_id = memcg_id;

	INIT_LIST_HEAD(&memcg->memcg_slab_caches);
@@ -4218,10 +4230,6 @@ static int __memcg_activate_kmem(struct mem_cgroup *memcg, 
out:

	memcg_resume_kmem_account();

	return err;



out_rmid:

	ida_simple_remove(&kmem_limited_groups, memcg_id);

	goto out;

}



static int memcg_activate_kmem(struct mem_cgroup *memcg,

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