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=-7.7 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,MAILING_LIST_MULTI, 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 64AFFC4361B for ; Tue, 15 Dec 2020 20:33:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0CFF622C7B for ; Tue, 15 Dec 2020 20:33:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CFF622C7B 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 A4BB46B0068; Tue, 15 Dec 2020 15:33:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9FAB86B006C; Tue, 15 Dec 2020 15:33:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E9E26B006E; Tue, 15 Dec 2020 15:33:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0070.hostedemail.com [216.40.44.70]) by kanga.kvack.org (Postfix) with ESMTP id 735DE6B0068 for ; Tue, 15 Dec 2020 15:33:06 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 3C04F181AEF32 for ; Tue, 15 Dec 2020 20:33:06 +0000 (UTC) X-FDA: 77596665972.25.shop50_621746b27426 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id 09D0B1804E3BB for ; Tue, 15 Dec 2020 20:33:06 +0000 (UTC) X-HE-Tag: shop50_621746b27426 X-Filterd-Recvd-Size: 3833 Received: from mail-ed1-f68.google.com (mail-ed1-f68.google.com [209.85.208.68]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Dec 2020 20:33:05 +0000 (UTC) Received: by mail-ed1-f68.google.com with SMTP id p22so22440384edu.11 for ; Tue, 15 Dec 2020 12:33:05 -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=HnIdZIbHofYFRuQmYpMAr+KqMcOINorVtwHcWuXO3CQ=; b=vDDe57R6klgFWHuh2HY3lU9Hse+4YOXW6G9FHSpk+R5Lwu/ePxlIzV1os6OnNraZat SHKaGNazTQ5cC/mxyhdKG4wReYKGicHSCkJm88LAtkC48osuGOT0i3+FWdnJaB47leHf iIou1yz7C33S5szb4x/1A93NvladUYWe8TP90XdAEjt/JP3inQ1f42Mj7UcTjXgqE6Ys FB3npC0z5IlASmY3btmSIe2+wY36PWxNHyPbLT8qaAf0nbaFUsPPR+XGLGM5cZBCj2go udW7rKICgaS0Ev69TvKLtrEporbt7P+6bRV6nbJjZI9p7UvPnonjSZhENKRZEPBvEzGM /ahA== 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=HnIdZIbHofYFRuQmYpMAr+KqMcOINorVtwHcWuXO3CQ=; b=NXeLo+6pa8m7xKAYgPr1F24EKbz8JBo0oW4ZRxARIGsTD97b+2pd285aQj2Q7mYumP /K15O/2ceZRqvhz6zYGAKHyR/A0ZAuSZJgn95eiKgholRMoFEUo5J0Ql4l3XvBcT3j/p Db0RRcj4FvgLufKW4WworsNBn70lOQMopvtB3wbv4+0zalUMGu1yDDjfSUMNpdsFrR2O a8m4/Dt75m7sYqyiXGu9UheBTm+sZVxs7DgeAWzjnaHj62Mpl1kxhkIfobkc0/mejjNK tDT2nZiqNjHReMDmXHQ9DsZBPOgrKFl0MV8QVOhj+jtMfeqNvpipY7k40SqqjfOMCswx yrTw== X-Gm-Message-State: AOAM530gd748bRoGXmP//gPmppyTUoFh0j1Nd0DsAEke+7MwMxj8V9DG zF9QGP11KOL0DWOCX65mS8efSR4HBNXRsnR2fAu9yWsi+hc= X-Google-Smtp-Source: ABdhPJzE/1t6NIjK7mvndb9OLxuvHdPZBWjgVPmyEBbMEyqiMi0B4DCaqEcPB8RGlchQ26lbTIqTqt55O1D6B3ysHWY= X-Received: by 2002:a05:6402:c95:: with SMTP id cm21mr31133119edb.294.1608064384485; Tue, 15 Dec 2020 12:33:04 -0800 (PST) MIME-Version: 1.0 References: <20201214223722.232537-1-shy828301@gmail.com> <20201214223722.232537-3-shy828301@gmail.com> <20201215140754.GD379720@cmpxchg.org> In-Reply-To: <20201215140754.GD379720@cmpxchg.org> From: Yang Shi Date: Tue, 15 Dec 2020 12:32:52 -0800 Message-ID: Subject: Re: [v2 PATCH 2/9] mm: memcontrol: use shrinker_rwsem to protect shrinker_maps allocation To: Johannes Weiner Cc: Roman Gushchin , Kirill Tkhai , Shakeel Butt , Dave Chinner , Michal Hocko , Andrew Morton , Linux MM , Linux FS-devel Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" 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 Tue, Dec 15, 2020 at 6:10 AM Johannes Weiner wrote: > > On Mon, Dec 14, 2020 at 02:37:15PM -0800, Yang Shi wrote: > > Since memcg_shrinker_map_size just can be changd under holding shrinker_rwsem > > exclusively, the read side can be protected by holding read lock, so it sounds > > superfluous to have a dedicated mutex. This should not exacerbate the contention > > to shrinker_rwsem since just one read side critical section is added. > > > > Signed-off-by: Yang Shi > > Acked-by: Johannes Weiner > > Thanks Yang, this is a step in the right direction. It would still be > nice to also drop memcg_shrinker_map_size and (trivially) derive that > value from shrinker_nr_max where necessary. It is duplicate state. Thanks! I will take a further look at it.