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: Suleiman Souhlal <suleiman@google.com> Signed-off-by: Glauber 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1f458cbf12
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3 changed files with 55 additions and 2 deletions
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@ -454,6 +454,7 @@ struct kmem_cache *
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__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
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void mem_cgroup_destroy_cache(struct kmem_cache *cachep);
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void kmem_cache_destroy_memcg_children(struct kmem_cache *s);
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/**
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* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
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@ -601,6 +602,10 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
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{
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return cachep;
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}
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static inline void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
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{
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}
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#endif /* CONFIG_MEMCG_KMEM */
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#endif /* _LINUX_MEMCONTROL_H */
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@ -2772,6 +2772,8 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
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memcg_check_events(memcg, page);
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}
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static DEFINE_MUTEX(set_limit_mutex);
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#ifdef CONFIG_MEMCG_KMEM
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static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
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{
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@ -3176,6 +3178,51 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
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return new_cachep;
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}
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void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
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{
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struct kmem_cache *c;
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int i;
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if (!s->memcg_params)
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return;
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if (!s->memcg_params->is_root_cache)
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return;
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/*
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* If the cache is being destroyed, we trust that there is no one else
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* requesting objects from it. Even if there are, the sanity checks in
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* kmem_cache_destroy should caught this ill-case.
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*
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* Still, we don't want anyone else freeing memcg_caches under our
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* noses, which can happen if a new memcg comes to life. As usual,
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* we'll take the set_limit_mutex to protect ourselves against this.
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*/
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mutex_lock(&set_limit_mutex);
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for (i = 0; i < memcg_limited_groups_array_size; i++) {
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c = s->memcg_params->memcg_caches[i];
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if (!c)
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continue;
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/*
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* We will now manually delete the caches, so to avoid races
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* we need to cancel all pending destruction workers and
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* proceed with destruction ourselves.
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*
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* kmem_cache_destroy() will call kmem_cache_shrink internally,
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* and that could spawn the workers again: it is likely that
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* the cache still have active pages until this very moment.
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* This would lead us back to mem_cgroup_destroy_cache.
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*
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* But that will not execute at all if the "dead" flag is not
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* set, so flip it down to guarantee we are in control.
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*/
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c->memcg_params->dead = false;
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cancel_delayed_work_sync(&c->memcg_params->destroy);
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kmem_cache_destroy(c);
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}
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mutex_unlock(&set_limit_mutex);
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}
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struct create_work {
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struct mem_cgroup *memcg;
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struct kmem_cache *cachep;
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@ -4284,8 +4331,6 @@ void mem_cgroup_print_bad_page(struct page *page)
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}
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#endif
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static DEFINE_MUTEX(set_limit_mutex);
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static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
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unsigned long long val)
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{
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@ -249,6 +249,9 @@ EXPORT_SYMBOL(kmem_cache_create);
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void kmem_cache_destroy(struct kmem_cache *s)
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{
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/* Destroy all the children caches if we aren't a memcg cache */
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kmem_cache_destroy_memcg_children(s);
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get_online_cpus();
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mutex_lock(&slab_mutex);
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s->refcount--;
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