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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 DBACAC433DB for ; Wed, 6 Jan 2021 11:36:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A23623100 for ; Wed, 6 Jan 2021 11:36:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726059AbhAFLgS (ORCPT ); Wed, 6 Jan 2021 06:36:18 -0500 Received: from relay.sw.ru ([185.231.240.75]:55910 "EHLO relay3.sw.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725788AbhAFLgR (ORCPT ); Wed, 6 Jan 2021 06:36:17 -0500 Received: from [192.168.15.143] by relay3.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1kx75B-00FdAy-9u; Wed, 06 Jan 2021 14:34:29 +0300 Subject: Re: [v3 PATCH 10/11] mm: memcontrol: reparent nr_deferred when memcg offline To: Yang Shi , guro@fb.com, shakeelb@google.com, david@fromorbit.com, hannes@cmpxchg.org, mhocko@suse.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210105225817.1036378-1-shy828301@gmail.com> <20210105225817.1036378-11-shy828301@gmail.com> From: Kirill Tkhai Message-ID: <777d47b3-65f7-5727-2d21-dbef93e7d1ed@virtuozzo.com> Date: Wed, 6 Jan 2021 14:34:39 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210105225817.1036378-11-shy828301@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06.01.2021 01:58, Yang Shi wrote: > Now shrinker's nr_deferred is per memcg for memcg aware shrinkers, add to parent's > corresponding nr_deferred when memcg offline. > > Signed-off-by: Yang Shi > --- > include/linux/memcontrol.h | 1 + > mm/memcontrol.c | 1 + > mm/vmscan.c | 29 +++++++++++++++++++++++++++++ > 3 files changed, 31 insertions(+) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 5599082df623..d1e52e916cc2 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -1586,6 +1586,7 @@ extern int memcg_alloc_shrinker_info(struct mem_cgroup *memcg); > extern void memcg_free_shrinker_info(struct mem_cgroup *memcg); > extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg, > int nid, int shrinker_id); > +extern void memcg_reparent_shrinker_deferred(struct mem_cgroup *memcg); > #else > #define mem_cgroup_sockets_enabled 0 > static inline void mem_cgroup_sk_alloc(struct sock *sk) { }; > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 126f1fd550c8..19e555675582 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5284,6 +5284,7 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) > page_counter_set_low(&memcg->memory, 0); > > memcg_offline_kmem(memcg); > + memcg_reparent_shrinker_deferred(memcg); > wb_memcg_offline(memcg); > > drain_all_stock(memcg); > diff --git a/mm/vmscan.c b/mm/vmscan.c > index d9795fb0f1c5..71056057d26d 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -396,6 +396,35 @@ static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, > return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); > } > > +void memcg_reparent_shrinker_deferred(struct mem_cgroup *memcg) > +{ > + int i, nid; > + long nr; > + struct mem_cgroup *parent; > + struct memcg_shrinker_info *child_info, *parent_info; > + > + parent = parent_mem_cgroup(memcg); > + if (!parent) > + parent = root_mem_cgroup; > + > + /* Prevent from concurrent shrinker_info expand */ > + down_read(&shrinker_rwsem); > + for_each_node(nid) { > + child_info = rcu_dereference_protected( > + memcg->nodeinfo[nid]->shrinker_info, > + true); > + parent_info = rcu_dereference_protected( > + parent->nodeinfo[nid]->shrinker_info, > + true); Simple assignment can't take such lots of space, we have to do something with that. Number of these rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, true) became too big, and we can't allow every of them takes 3 lines. We should introduce a short helper to dereferrence this, so we will be able to give out attention to really difficult logic instead of wasting it on parsing this. child_info = memcg_shrinker_info(memcg, nid); or child_info = memcg_shrinker_info_protected(memcg, nid); Both of them fit in single line. struct memcg_shrinker_info *memcg_shrinker_info_protected( struct mem_cgroup *memcg, int nid) { return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, lockdep_assert_held(&shrinker_rwsem)); } > + for (i = 0; i < shrinker_nr_max; i++) { > + nr = atomic_long_read(&child_info->nr_deferred[i]); > + atomic_long_add(nr, > + &parent_info->nr_deferred[i]); Why new line is here? In case of you merge it up, it will be even shorter then previous line. > + } > + } > + up_read(&shrinker_rwsem); > +} > + > static bool cgroup_reclaim(struct scan_control *sc) > { > return sc->target_mem_cgroup; >