From d797b7d05405c519f7b62ea69a75cea1883863b2 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 6 Aug 2020 23:21:14 -0700 Subject: mm: memcg/slab: simplify memcg cache creation Because the number of non-root kmem_caches doesn't depend on the number of memory cgroups anymore and is generally not very big, there is no more need for a dedicated workqueue. Also, as there is no more need to pass any arguments to the memcg_create_kmem_cache() except the root kmem_cache, it's possible to just embed the work structure into the kmem_cache and avoid the dynamic allocation of the work structure. This will also simplify the synchronization: for each root kmem_cache there is only one work. So there will be no more concurrent attempts to create a non-root kmem_cache for a root kmem_cache: the second and all following attempts to queue the work will fail. On the kmem_cache destruction path there is no more need to call the expensive flush_workqueue() and wait for all pending works to be finished. Instead, cancel_work_sync() can be used to cancel/wait for only one work. Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Link: http://lkml.kernel.org/r/20200623174037.3951353-14-guro@fb.com Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 48 +----------------------------------------------- 1 file changed, 1 insertion(+), 47 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 874704c4a48a..c713867e496d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -399,8 +399,6 @@ void memcg_put_cache_ids(void) */ DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key); EXPORT_SYMBOL(memcg_kmem_enabled_key); - -struct workqueue_struct *memcg_kmem_cache_wq; #endif static int memcg_shrinker_map_size; @@ -2902,39 +2900,6 @@ static void memcg_free_cache_id(int id) ida_simple_remove(&memcg_cache_ida, id); } -struct memcg_kmem_cache_create_work { - struct kmem_cache *cachep; - struct work_struct work; -}; - -static void memcg_kmem_cache_create_func(struct work_struct *w) -{ - struct memcg_kmem_cache_create_work *cw = - container_of(w, struct memcg_kmem_cache_create_work, work); - struct kmem_cache *cachep = cw->cachep; - - memcg_create_kmem_cache(cachep); - - kfree(cw); -} - -/* - * Enqueue the creation of a per-memcg kmem_cache. - */ -static void memcg_schedule_kmem_cache_create(struct kmem_cache *cachep) -{ - struct memcg_kmem_cache_create_work *cw; - - cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN); - if (!cw) - return; - - cw->cachep = cachep; - INIT_WORK(&cw->work, memcg_kmem_cache_create_func); - - queue_work(memcg_kmem_cache_wq, &cw->work); -} - /** * memcg_kmem_get_cache: select memcg or root cache for allocation * @cachep: the original global kmem cache @@ -2951,7 +2916,7 @@ struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep) memcg_cachep = READ_ONCE(cachep->memcg_params.memcg_cache); if (unlikely(!memcg_cachep)) { - memcg_schedule_kmem_cache_create(cachep); + queue_work(system_wq, &cachep->memcg_params.work); return cachep; } @@ -7022,17 +6987,6 @@ static int __init mem_cgroup_init(void) { int cpu, node; -#ifdef CONFIG_MEMCG_KMEM - /* - * Kmem cache creation is mostly done with the slab_mutex held, - * so use a workqueue with limited concurrency to avoid stalling - * all worker threads in case lots of cgroups are created and - * destroyed simultaneously. - */ - memcg_kmem_cache_wq = alloc_workqueue("memcg_kmem_cache", 0, 1); - BUG_ON(!memcg_kmem_cache_wq); -#endif - cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL, memcg_hotplug_cpu_dead); -- cgit v1.2.3