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-rw-r--r--include/linux/memcontrol.h1
-rw-r--r--include/linux/slab.h2
-rw-r--r--mm/memcontrol.c63
-rw-r--r--mm/slab.h7
4 files changed, 4 insertions, 69 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 5155d09e749d..087a45314181 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -509,7 +509,6 @@ __memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size);
void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size);
-void mem_cgroup_destroy_cache(struct kmem_cache *cachep);
int __kmem_cache_destroy_memcg_children(struct kmem_cache *s);
/**
diff --git a/include/linux/slab.h b/include/linux/slab.h
index a6aab2c0dfc5..905541dd3778 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -524,7 +524,6 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
* @memcg: pointer to the memcg this cache belongs to
* @list: list_head for the list of all caches in this memcg
* @root_cache: pointer to the global, root cache, this cache was derived from
- * @dead: set to true after the memcg dies; the cache may still be around.
* @nr_pages: number of pages that belongs to this cache.
* @destroy: worker to be called whenever we are ready, or believe we may be
* ready, to destroy this cache.
@@ -540,7 +539,6 @@ struct memcg_cache_params {
struct mem_cgroup *memcg;
struct list_head list;
struct kmem_cache *root_cache;
- bool dead;
atomic_t nr_pages;
struct work_struct destroy;
};
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9f4ff49c6add..6b1c45ced733 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3277,60 +3277,11 @@ static void kmem_cache_destroy_work_func(struct work_struct *w)
cachep = memcg_params_to_cache(p);
- /*
- * If we get down to 0 after shrink, we could delete right away.
- * However, memcg_release_pages() already puts us back in the workqueue
- * in that case. If we proceed deleting, we'll get a dangling
- * reference, and removing the object from the workqueue in that case
- * is unnecessary complication. We are not a fast path.
- *
- * Note that this case is fundamentally different from racing with
- * shrink_slab(): if memcg_cgroup_destroy_cache() is called in
- * kmem_cache_shrink, not only we would be reinserting a dead cache
- * into the queue, but doing so from inside the worker racing to
- * destroy it.
- *
- * So if we aren't down to zero, we'll just schedule a worker and try
- * again
- */
- if (atomic_read(&cachep->memcg_params->nr_pages) != 0)
- kmem_cache_shrink(cachep);
- else
+ kmem_cache_shrink(cachep);
+ if (atomic_read(&cachep->memcg_params->nr_pages) == 0)
kmem_cache_destroy(cachep);
}
-void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
-{
- if (!cachep->memcg_params->dead)
- return;
-
- /*
- * There are many ways in which we can get here.
- *
- * We can get to a memory-pressure situation while the delayed work is
- * still pending to run. The vmscan shrinkers can then release all
- * cache memory and get us to destruction. If this is the case, we'll
- * be executed twice, which is a bug (the second time will execute over
- * bogus data). In this case, cancelling the work should be fine.
- *
- * But we can also get here from the worker itself, if
- * kmem_cache_shrink is enough to shake all the remaining objects and
- * get the page count to 0. In this case, we'll deadlock if we try to
- * cancel the work (the worker runs with an internal lock held, which
- * is the same lock we would hold for cancel_work_sync().)
- *
- * Since we can't possibly know who got us here, just refrain from
- * running if there is already work pending
- */
- if (work_pending(&cachep->memcg_params->destroy))
- return;
- /*
- * We have to defer the actual destroying to a workqueue, because
- * we might currently be in a context that cannot sleep.
- */
- schedule_work(&cachep->memcg_params->destroy);
-}
-
int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
{
struct kmem_cache *c;
@@ -3356,16 +3307,7 @@ int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
* 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_work_sync(&c->memcg_params->destroy);
kmem_cache_destroy(c);
@@ -3387,7 +3329,6 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
mutex_lock(&memcg->slab_caches_mutex);
list_for_each_entry(params, &memcg->memcg_slab_caches, list) {
cachep = memcg_params_to_cache(params);
- cachep->memcg_params->dead = true;
schedule_work(&cachep->memcg_params->destroy);
}
mutex_unlock(&memcg->slab_caches_mutex);
diff --git a/mm/slab.h b/mm/slab.h
index d85d59803d5f..b59447ac4533 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -129,11 +129,8 @@ static inline void memcg_bind_pages(struct kmem_cache *s, int order)
static inline void memcg_release_pages(struct kmem_cache *s, int order)
{
- if (is_root_cache(s))
- return;
-
- if (atomic_sub_and_test((1 << order), &s->memcg_params->nr_pages))
- mem_cgroup_destroy_cache(s);
+ if (!is_root_cache(s))
+ atomic_sub(1 << order, &s->memcg_params->nr_pages);
}
static inline bool slab_equal_or_root(struct kmem_cache *s,