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 B9766C4361B for ; Tue, 15 Dec 2020 20:36:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 915E022510 for ; Tue, 15 Dec 2020 20:36:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727649AbgLOUgN (ORCPT ); Tue, 15 Dec 2020 15:36:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728575AbgLOUdq (ORCPT ); Tue, 15 Dec 2020 15:33:46 -0500 Received: from mail-ed1-x542.google.com (mail-ed1-x542.google.com [IPv6:2a00:1450:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9663C06179C; Tue, 15 Dec 2020 12:33:05 -0800 (PST) Received: by mail-ed1-x542.google.com with SMTP id j16so57922edr.0; 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=esoodBaVRRplqM6imea1OODvuyupweNfGJkhmiEJ4YI6CBhzu4HyvBpDhzpVDMPDbo SEyCMjWhUF8FrL36Q5bTByOMoLFcB0N+q1ktIEXFvK+hiXT5xTZcpMKULZffl5VEPDSo C6thwjTyBnsJ/qmawoe4dExOjYO4E7pYZL78KceYkAUiEwboCA8WpXY5OZRObsGHMtH3 Ly0l/5wTOPGnq5DGExSItFSnDGrvBDtAxPojgl8M3asPbumazjOC36mN2w/DAcntAHiu 0EeuWC7GbQ8gPZPXQy4EqxyPlN36G7Iqv5RcB8R8Ye9HQ5H+knoRcafS3zaem2AbYqhE SZlQ== X-Gm-Message-State: AOAM530pCkbsmHKsZD1IQ3Hm6N8zwP6v6ql3PN8E42aL91iAfvNfAjib qchd4nKoqKTfuTlg1DDN/p1y3z2Sw7ceq8W6+ss= 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" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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.