Creating a lot of cgroups at the same time might stall all worker threads with kmem cache creation works, because kmem cache creation is done with the slab_mutex held. To prevent that from happening, let's use a special workqueue for kmem cache creation with max in-flight work items equal to 1. Link: https://bugzilla.kernel.org/show_bug.cgi?id=172981 Signed-off-by: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Reported-by: Doug Smythies <dsmythies@xxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> --- mm/memcontrol.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4be518d4e68a..c1efe59e3a20 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2175,6 +2175,8 @@ struct memcg_kmem_cache_create_work { struct work_struct work; }; +static struct workqueue_struct *memcg_kmem_cache_create_wq; + static void memcg_kmem_cache_create_func(struct work_struct *w) { struct memcg_kmem_cache_create_work *cw = @@ -2206,7 +2208,7 @@ static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, cw->cachep = cachep; INIT_WORK(&cw->work, memcg_kmem_cache_create_func); - schedule_work(&cw->work); + queue_work(memcg_kmem_cache_create_wq, &cw->work); } static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, @@ -5794,6 +5796,17 @@ static int __init mem_cgroup_init(void) { int cpu, node; +#ifndef CONFIG_SLOB + /* + * Kmem cache creation is mostly done with the slab_mutex held, + * so use a special workqueue to avoid stalling all worker + * threads in case lots of cgroups are created simultaneously. + */ + memcg_kmem_cache_create_wq = + alloc_workqueue("memcg_kmem_cache_create", 0, 1); + BUG_ON(!memcg_kmem_cache_create_wq); +#endif + hotcpu_notifier(memcg_cpu_hotplug_callback, 0); for_each_possible_cpu(cpu) -- 2.1.4 -- 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>