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

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
......@@ -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 */
......@@ -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)
{
......
......@@ -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--;
......
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