From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BC82C433E1 for ; Fri, 7 Aug 2020 06:21:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33B8B2177B for ; Fri, 7 Aug 2020 06:21:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781277; bh=Fhu6cQTbKmBdAAVvI4mhNXkwC0uRFIVD/XvH3G4l5u0=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=2mf8/iVs0c3KJ4kx9QeGHsg0J/irsWvY3/CIBs0rxwpzhTw0VrOsf50/JMg5PtaoT pFNByweGJvenV95PAaIQQJefcy/xMzq+6aN5gG3IaHXphK2/Oh+uSqjKYVqJ33JJoO 7wRumaNtvLZZ4vrpFyy30DmRl24GYh/ELLM7TA9g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726205AbgHGGVQ (ORCPT ); Fri, 7 Aug 2020 02:21:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:57360 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgHGGVQ (ORCPT ); Fri, 7 Aug 2020 02:21:16 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 99CDC22CAF; Fri, 7 Aug 2020 06:21:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781275; bh=Fhu6cQTbKmBdAAVvI4mhNXkwC0uRFIVD/XvH3G4l5u0=; h=Date:From:To:Subject:In-Reply-To:From; b=jAShDOzajjZpL54sYHhpgdEJXHsHLoq5LlBpkHpcfXNBLYffXfvs8zGH6EKbjnPYL UGxh3C8dU0i5gMG12k6FTdMmfwDGincoqTGp9+MmneYeJDZI45MuP79+dmulPjdPk6 jYaoz3uZ0OAU9h1WGmo3e5d1fmWnKQTn4Age7+pg= Date: Thu, 06 Aug 2020 23:21:14 -0700 From: Andrew Morton To: akpm@linux-foundation.org, cl@linux.com, guro@fb.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, shakeelb@google.com, tj@kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 074/163] mm: memcg/slab: simplify memcg cache creation Message-ID: <20200807062114.A811_SKgY%akpm@linux-foundation.org> In-Reply-To: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Roman Gushchin 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. Link: http://lkml.kernel.org/r/20200623174037.3951353-14-guro@fb.com Signed-off-by: Roman Gushchin Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Signed-off-by: Andrew Morton --- include/linux/memcontrol.h | 1 mm/memcontrol.c | 48 ----------------------------------- mm/slab.h | 2 + mm/slab_common.c | 22 ++++++++-------- 4 files changed, 15 insertions(+), 58 deletions(-) --- a/include/linux/memcontrol.h~mm-memcg-slab-simplify-memcg-cache-creation +++ a/include/linux/memcontrol.h @@ -1418,7 +1418,6 @@ int obj_cgroup_charge(struct obj_cgroup void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size); extern struct static_key_false memcg_kmem_enabled_key; -extern struct workqueue_struct *memcg_kmem_cache_wq; extern int memcg_nr_cache_ids; void memcg_get_cache_ids(void); --- a/mm/memcontrol.c~mm-memcg-slab-simplify-memcg-cache-creation +++ a/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( 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); --- a/mm/slab_common.c~mm-memcg-slab-simplify-memcg-cache-creation +++ a/mm/slab_common.c @@ -134,10 +134,18 @@ int __kmem_cache_alloc_bulk(struct kmem_ LIST_HEAD(slab_root_caches); +static void memcg_kmem_cache_create_func(struct work_struct *work) +{ + struct kmem_cache *cachep = container_of(work, struct kmem_cache, + memcg_params.work); + memcg_create_kmem_cache(cachep); +} + void slab_init_memcg_params(struct kmem_cache *s) { s->memcg_params.root_cache = NULL; s->memcg_params.memcg_cache = NULL; + INIT_WORK(&s->memcg_params.work, memcg_kmem_cache_create_func); } static void init_memcg_params(struct kmem_cache *s, @@ -586,15 +594,9 @@ static int shutdown_memcg_caches(struct return 0; } -static void flush_memcg_workqueue(struct kmem_cache *s) +static void cancel_memcg_cache_creation(struct kmem_cache *s) { - /* - * SLAB and SLUB create memcg kmem_caches through workqueue and SLUB - * deactivates the memcg kmem_caches through workqueue. Make sure all - * previous workitems on workqueue are processed. - */ - if (likely(memcg_kmem_cache_wq)) - flush_workqueue(memcg_kmem_cache_wq); + cancel_work_sync(&s->memcg_params.work); } #else static inline int shutdown_memcg_caches(struct kmem_cache *s) @@ -602,7 +604,7 @@ static inline int shutdown_memcg_caches( return 0; } -static inline void flush_memcg_workqueue(struct kmem_cache *s) +static inline void cancel_memcg_cache_creation(struct kmem_cache *s) { } #endif /* CONFIG_MEMCG_KMEM */ @@ -621,7 +623,7 @@ void kmem_cache_destroy(struct kmem_cach if (unlikely(!s)) return; - flush_memcg_workqueue(s); + cancel_memcg_cache_creation(s); get_online_cpus(); get_online_mems(); --- a/mm/slab.h~mm-memcg-slab-simplify-memcg-cache-creation +++ a/mm/slab.h @@ -45,12 +45,14 @@ struct kmem_cache { * @memcg_cache: pointer to memcg kmem cache, used by all non-root memory * cgroups. * @root_caches_node: list node for slab_root_caches list. + * @work: work struct used to create the non-root cache. */ struct memcg_cache_params { struct kmem_cache *root_cache; struct kmem_cache *memcg_cache; struct list_head __root_caches_node; + struct work_struct work; }; #endif /* CONFIG_SLOB */ _