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=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 E9952C433E6 for ; Mon, 8 Mar 2021 18:15:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B68866518A for ; Mon, 8 Mar 2021 18:15:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230320AbhCHSP2 (ORCPT ); Mon, 8 Mar 2021 13:15:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230116AbhCHSPQ (ORCPT ); Mon, 8 Mar 2021 13:15:16 -0500 Received: from mail-ej1-x62a.google.com (mail-ej1-x62a.google.com [IPv6:2a00:1450:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80F4BC06174A; Mon, 8 Mar 2021 10:15:16 -0800 (PST) Received: by mail-ej1-x62a.google.com with SMTP id mm21so22183872ejb.12; 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=n9yDtv+Wb6KpkZENS/Juvp+hOpFUAiiW7HdDpVimsyC3AUFm7eJi/URX8LKXx8nK9I f3IZCnRnxnXt6NGoGoO/jNGGZWNA37TZPkdg6kuRgebooqXPHZ33YlRhPk1ht2A9w80C I0WD3sSld1Al6z12MDO+KhGaAZBcFOedcsvSvldUjZ4aP8CBea+ufHsiKkwHqgaCyUdB ZVNuSnhfSZXtL+qvaCvgU2ifzWlSuGpUnnWNTKnTyp+CyVUEsRjHLx+VoRtTQxtOmmC1 eV0NVlD0ll5yGV4ym07r2XQ8PWF1rAn4iP+eyizgJGTx7+kdOuO+/szfgD/ZoGD5gZqb OkOQ== X-Gm-Message-State: AOAM531zegPxF8G7Z5pKAals/xeEVlRLhKhZUHiN8BdTbBXU1xqPGhSC KutNXC70hAkQxgLe8oTQ8homtWke3Oelgw5zV/8= 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" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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