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 2719DC433E0 for ; Wed, 6 Jan 2021 10:17:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C68082310D for ; Wed, 6 Jan 2021 10:17:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726811AbhAFKQv (ORCPT ); Wed, 6 Jan 2021 05:16:51 -0500 Received: from relay.sw.ru ([185.231.240.75]:55872 "EHLO relay3.sw.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726379AbhAFKQu (ORCPT ); Wed, 6 Jan 2021 05:16:50 -0500 Received: from [192.168.15.143] by relay3.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1kx5qI-00Fcnd-ME; Wed, 06 Jan 2021 13:15:02 +0300 Subject: Re: [v3 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map_size 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> <20210105225817.1036378-5-shy828301@gmail.com> From: Kirill Tkhai Message-ID: <955422c5-0703-e9fb-f309-6ed6b5fc0e0a@virtuozzo.com> Date: Wed, 6 Jan 2021 13:15:13 +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: <20210105225817.1036378-5-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: > Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the > map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both. > Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the > bit map. > > Signed-off-by: Yang Shi > --- > mm/vmscan.c | 12 ++++-------- > 1 file changed, 4 insertions(+), 8 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index ddb9f972f856..8da765a85569 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -185,8 +185,7 @@ static LIST_HEAD(shrinker_list); > static DECLARE_RWSEM(shrinker_rwsem); > > #ifdef CONFIG_MEMCG > - > -static int memcg_shrinker_map_size; > +static int shrinker_nr_max; > > static void memcg_free_shrinker_map_rcu(struct rcu_head *head) > { > @@ -248,7 +247,7 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) > return 0; > > down_read(&shrinker_rwsem); > - size = memcg_shrinker_map_size; > + size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); > for_each_node(nid) { > map = kvzalloc(sizeof(*map) + size, GFP_KERNEL); > if (!map) { > @@ -269,7 +268,7 @@ static int memcg_expand_shrinker_maps(int new_id) > struct mem_cgroup *memcg; > > size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long); > - old_size = memcg_shrinker_map_size; > + old_size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); > if (size <= old_size) > return 0; These bunch of DIV_ROUND_UP() looks too complex. Since now all the shrinker maps allocation logic in the only file, can't we simplify this to look better? I mean something like below to merge in your patch: diff --git a/mm/vmscan.c b/mm/vmscan.c index b951c289ef3a..27b6371a1656 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -247,7 +247,7 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) return 0; down_read(&shrinker_rwsem); - size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); + size = shrinker_nr_max / BITS_PER_BYTE; for_each_node(nid) { map = kvzalloc(sizeof(*map) + size, GFP_KERNEL); if (!map) { @@ -264,13 +264,11 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) static int memcg_expand_shrinker_maps(int new_id) { - int size, old_size, ret = 0; + int size, old_size, new_nr_max, ret = 0; struct mem_cgroup *memcg; size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long); - old_size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); - if (size <= old_size) - return 0; + new_nr_max = size * BITS_PER_BYTE; if (!root_mem_cgroup) goto out; @@ -287,6 +285,9 @@ static int memcg_expand_shrinker_maps(int new_id) } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); out: + if (ret == 0) + shrinker_nr_max = new_nr_max; + return ret; } @@ -334,8 +335,6 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) idr_remove(&shrinker_idr, id); goto unlock; } - - shrinker_nr_max = id + 1; } shrinker->id = id; ret = 0;