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Commit 7cf27982 authored by Glauber Costa's avatar Glauber Costa Committed by Linus Torvalds
Browse files

memcg/sl[au]b: track all the memcg children of a kmem_cache 



This enables us to remove all the children of a kmem_cache being
destroyed, if for example the kernel module it's being used in gets
unloaded.  Otherwise, the children will still point to the destroyed
parent.

Signed-off-by: default avatarSuleiman Souhlal <suleiman@google.com>
Signed-off-by: default avatarGlauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f458cbf

include/linux/memcontrol.h

+5 −0
Original line number Diff line number Diff line
@@ -454,6 +454,7 @@ struct kmem_cache * 
__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);



void mem_cgroup_destroy_cache(struct kmem_cache *cachep);

void kmem_cache_destroy_memcg_children(struct kmem_cache *s);



/**

 * memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
@@ -601,6 +602,10 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp) 
{

	return cachep;

}



static inline void kmem_cache_destroy_memcg_children(struct kmem_cache *s)

{

}

#endif /* CONFIG_MEMCG_KMEM */

#endif /* _LINUX_MEMCONTROL_H */

mm/memcontrol.c

+47 −2
Original line number Diff line number Diff line
@@ -2772,6 +2772,8 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, 
	memcg_check_events(memcg, page);

}



static DEFINE_MUTEX(set_limit_mutex);



#ifdef CONFIG_MEMCG_KMEM

static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)

{
@@ -3176,6 +3178,51 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, 
	return new_cachep;

}



void kmem_cache_destroy_memcg_children(struct kmem_cache *s)

{

	struct kmem_cache *c;

	int i;



	if (!s->memcg_params)

		return;

	if (!s->memcg_params->is_root_cache)

		return;



	/*

	 * If the cache is being destroyed, we trust that there is no one else

	 * requesting objects from it. Even if there are, the sanity checks in

	 * kmem_cache_destroy should caught this ill-case.

	 *

	 * Still, we don't want anyone else freeing memcg_caches under our

	 * noses, which can happen if a new memcg comes to life. As usual,

	 * we'll take the set_limit_mutex to protect ourselves against this.

	 */

	mutex_lock(&set_limit_mutex);

	for (i = 0; i < memcg_limited_groups_array_size; i++) {

		c = s->memcg_params->memcg_caches[i];

		if (!c)

			continue;



		/*

		 * We will now manually delete the caches, so to avoid races

		 * we need to cancel all pending destruction workers and

		 * proceed with destruction ourselves.

		 *

		 * kmem_cache_destroy() will call kmem_cache_shrink internally,

		 * and that could spawn the workers again: it is likely that

		 * the cache still have active pages until this very moment.

		 * This would lead us back to mem_cgroup_destroy_cache.

		 *

		 * But that will not execute at all if the "dead" flag is not

		 * set, so flip it down to guarantee we are in control.

		 */

		c->memcg_params->dead = false;

		cancel_delayed_work_sync(&c->memcg_params->destroy);

		kmem_cache_destroy(c);

	}

	mutex_unlock(&set_limit_mutex);

}



struct create_work {

	struct mem_cgroup *memcg;

	struct kmem_cache *cachep;
@@ -4284,8 +4331,6 @@ void mem_cgroup_print_bad_page(struct page *page) 
}

#endif



static DEFINE_MUTEX(set_limit_mutex);



static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,

				unsigned long long val)

{

mm/slab_common.c

+3 −0
Original line number Diff line number Diff line
@@ -249,6 +249,9 @@ EXPORT_SYMBOL(kmem_cache_create); 


void kmem_cache_destroy(struct kmem_cache *s)

{

	/* Destroy all the children caches if we aren't a memcg cache */

	kmem_cache_destroy_memcg_children(s);



	get_online_cpus();

	mutex_lock(&slab_mutex);

	s->refcount--;