Since a dead memcg cache is destroyed only after the last slab allocated to it is freed, we must disable caching of free objects/slabs for such caches, otherwise they will be hanging around forever. For SLAB that means we must disable per cpu free object arrays and make free_block always discard empty slabs irrespective of node's free_limit. To disable per cpu arrays, we free them on kmem_cache_shrink (see drain_cpu_caches -> do_drain) and make __cache_free fall back to free_block if there is no per cpu array. Also, we have to disable allocation of per cpu arrays on cpu hotplug for dead caches (see cpuup_prepare, __do_tune_cpucache). After we disabled free objects/slabs caching, there is no need to reap those caches periodically. Moreover, it will only result in slowdown. So we also make cache_reap skip then. Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> --- mm/slab.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index b3af82419251..7e91f5f1341d 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -1210,6 +1210,9 @@ static int cpuup_prepare(long cpu) struct array_cache *shared = NULL; struct array_cache **alien = NULL; + if (memcg_cache_dead(cachep)) + continue; + nc = alloc_arraycache(node, cachep->limit, cachep->batchcount, GFP_KERNEL); if (!nc) @@ -2411,10 +2414,18 @@ static void do_drain(void *arg) check_irq_off(); ac = cpu_cache_get(cachep); + if (!ac) + return; + spin_lock(&cachep->node[node]->list_lock); free_block(cachep, ac->entry, ac->avail, node); spin_unlock(&cachep->node[node]->list_lock); ac->avail = 0; + + if (memcg_cache_dead(cachep)) { + cachep->array[smp_processor_id()] = NULL; + kfree(ac); + } } static void drain_cpu_caches(struct kmem_cache *cachep) @@ -3368,7 +3379,8 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects, /* fixup slab chains */ if (page->active == 0) { - if (n->free_objects > n->free_limit) { + if (n->free_objects > n->free_limit || + memcg_cache_dead(cachep)) { n->free_objects -= cachep->num; /* No need to drop any previously held * lock here, even if we have a off-slab slab @@ -3462,6 +3474,17 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp, kmemcheck_slab_free(cachep, objp, cachep->object_size); +#ifdef CONFIG_MEMCG_KMEM + if (unlikely(!ac)) { + int nodeid = page_to_nid(virt_to_page(objp)); + + spin_lock(&cachep->node[nodeid]->list_lock); + free_block(cachep, &objp, 1, nodeid); + spin_unlock(&cachep->node[nodeid]->list_lock); + return; + } +#endif + /* * Skip calling cache_free_alien() when the platform is not numa. * This will avoid cache misses that happen while accessing slabp (which @@ -3803,6 +3826,9 @@ static int __do_tune_cpucache(struct kmem_cache *cachep, int limit, struct ccupdate_struct *new; int i; + if (memcg_cache_dead(cachep)) + return 0; + new = kzalloc(sizeof(*new) + nr_cpu_ids * sizeof(struct array_cache *), gfp); if (!new) @@ -3988,6 +4014,9 @@ static void cache_reap(struct work_struct *w) list_for_each_entry(searchp, &slab_caches, list) { check_irq_on(); + if (memcg_cache_dead(searchp)) + continue; + /* * We only take the node lock if absolutely necessary and we * have established with reasonable certainty that -- 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>