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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 7AE98C433E6 for ; Mon, 8 Mar 2021 18:15:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 248EA6518A for ; Mon, 8 Mar 2021 18:15:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 248EA6518A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7AAEB8D0057; Mon, 8 Mar 2021 13:15:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 781598D001D; Mon, 8 Mar 2021 13:15:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 649EC8D0057; Mon, 8 Mar 2021 13:15:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0209.hostedemail.com [216.40.44.209]) by kanga.kvack.org (Postfix) with ESMTP id 49D678D001D for ; Mon, 8 Mar 2021 13:15:22 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 068A28249980 for ; Mon, 8 Mar 2021 18:15:22 +0000 (UTC) X-FDA: 77897509284.30.33912FB Received: from mail-ej1-f49.google.com (mail-ej1-f49.google.com [209.85.218.49]) by imf11.hostedemail.com (Postfix) with ESMTP id AE5B92000DAB for ; Mon, 8 Mar 2021 18:15:12 +0000 (UTC) Received: by mail-ej1-f49.google.com with SMTP id c10so22204820ejx.9 for ; Mon, 08 Mar 2021 10:15:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=g/bzyPjovQ9TJfpqIkZJGibSjbqLtnRGGO1V2kB7/2Q=; b=oT47EDYu5ZrDjIsPLw10d/GmM4ySkio4jkFzzhG3F1k2nUmyG4zpwIg9brdLIjhvH7 qQurFccmVjEpKc5/3/eeY+4IEo1je2kAdN8RMsGWgswPfZb+3T8oSRWQtnNeNNfdWjhP 0A1rR8InatWETyJvi00eTrVWuScMq/s38yA80bWk7hvcAoWsYdci6cI5m7P0wHbSJyzb a3Lv2ZdqVlYr6S0bNxxgcOFaruzl/LaWJhdD5mSzEhqx0A/ID5uknvSuW16TpX5XeDsP mXCNbqMQgxSSvwm2z5mqFNbOeKOYXS1siv4Gi/c1GzEDhpbpqv6dun/zFyYpfm4+K7pt rCNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=g/bzyPjovQ9TJfpqIkZJGibSjbqLtnRGGO1V2kB7/2Q=; b=TFoNRBPajLGYhSGjq59hRSq9yscqJVpUmPVEmfvvkHsRViOp/pM/BaHfFvEGRYnTS2 bPNoE5mAYjNOFpJtA4vb0iBmedJy88KYMgDqd7iiokwv5A0YW8EHjJm8qmINMGtDq0QG e8pDJpKOtY7WMH1V5swjxEiI/cg2H84d5Zqg4g66andN7lmq1tXotkp1Elpz1olRcJQn CenskqtyXfwsN7DYqRWucjpNUWfn7jcyaUI6YCV9I8sfMs0QY6jeF1LhyapkzVYbTJCB ZlON0CnwK3LYIUGVcAM0QR1X2N2B7zZMX+/lq2PD7fiqrIllW6KoI4E3KpDWSSKxYRiA GckQ== X-Gm-Message-State: AOAM5315tqq0xWqng7uiT94KI6TZEIMR3NF+jXJ+4rGY4f63OpdW5JH+ NkmZWZKIvNO79uoKk8rspkXvo6BgTH5tHY22lBI= X-Google-Smtp-Source: ABdhPJzEtTVkv8kuvlaSOiCjwhpHgBuYuDk4ONeS1aBsrVoMOmnjPFX7SSO1+yQH37wno17IK5bLkfwFj6HxNQFjjLA= X-Received: by 2002:a17:906:789:: with SMTP id l9mr15985654ejc.161.1615227315315; Mon, 08 Mar 2021 10:15:15 -0800 (PST) MIME-Version: 1.0 References: <20210217001322.2226796-1-shy828301@gmail.com> <20210217001322.2226796-6-shy828301@gmail.com> <20210308145444.GN2696@paulmck-ThinkPad-P72> In-Reply-To: <20210308145444.GN2696@paulmck-ThinkPad-P72> From: Yang Shi Date: Mon, 8 Mar 2021 10:15:03 -0800 Message-ID: Subject: Re: [v8 PATCH 05/13] mm: vmscan: use kvfree_rcu instead of call_rcu To: paulmck@kernel.org Cc: Shakeel Butt , Roman Gushchin , Kirill Tkhai , Vlastimil Babka , Dave Chinner , Johannes Weiner , Michal Hocko , Andrew Morton , Linux MM , linux-fsdevel , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AE5B92000DAB X-Stat-Signature: 9sc8dt7qstdki677sf17o4hyhexezzmc Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-ej1-f49.google.com; client-ip=209.85.218.49 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615227312-990914 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Mar 8, 2021 at 6:54 AM Paul E. McKenney wrote: > > On Sun, Mar 07, 2021 at 10:13:04PM -0800, Shakeel Butt wrote: > > On Tue, Feb 16, 2021 at 4:13 PM Yang Shi wrote: > > > > > > Using kvfree_rcu() to free the old shrinker_maps instead of call_rcu(). > > > We don't have to define a dedicated callback for call_rcu() anymore. > > > > > > Signed-off-by: Yang Shi > > > --- > > > mm/vmscan.c | 7 +------ > > > 1 file changed, 1 insertion(+), 6 deletions(-) > > > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > > index 2e753c2516fa..c2a309acd86b 100644 > > > --- a/mm/vmscan.c > > > +++ b/mm/vmscan.c > > > @@ -192,11 +192,6 @@ static inline int shrinker_map_size(int nr_items) > > > return (DIV_ROUND_UP(nr_items, BITS_PER_LONG) * sizeof(unsigned long)); > > > } > > > > > > -static void free_shrinker_map_rcu(struct rcu_head *head) > > > -{ > > > - kvfree(container_of(head, struct memcg_shrinker_map, rcu)); > > > -} > > > - > > > static int expand_one_shrinker_map(struct mem_cgroup *memcg, > > > int size, int old_size) > > > { > > > @@ -219,7 +214,7 @@ static int expand_one_shrinker_map(struct mem_cgroup *memcg, > > > memset((void *)new->map + old_size, 0, size - old_size); > > > > > > rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new); > > > - call_rcu(&old->rcu, free_shrinker_map_rcu); > > > + kvfree_rcu(old); > > > > Please use kvfree_rcu(old, rcu) instead of kvfree_rcu(old). The single > > param can call synchronize_rcu(). > > Especially given that you already have the ->rcu field that the > two-argument form requires. > > The reason for using the single-argument form is when you have lots of > little data structures, such that getting rid of that rcu_head structure > is valuable enough to be worth the occasional call to synchronize_rcu(). > However, please note that this call to synchronize_rcu() happens only > under OOM conditions. Thanks, Shakeel and Paul. I didn't realize the difference. Will use the two params form in the new version. > > Thanx, Paul