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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 9386EC04E84 for ; Tue, 28 May 2019 22:03:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 59A2C20717 for ; Tue, 28 May 2019 22:03:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="ToLngH1j" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 59A2C20717 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cmpxchg.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E336C6B028F; Tue, 28 May 2019 18:03:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DE3C96B0290; Tue, 28 May 2019 18:03:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C84146B0291; Tue, 28 May 2019 18:03:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) by kanga.kvack.org (Postfix) with ESMTP id 8FEA36B028F for ; Tue, 28 May 2019 18:03:57 -0400 (EDT) Received: by mail-pg1-f198.google.com with SMTP id e69so209985pgc.7 for ; Tue, 28 May 2019 15:03:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=ZB6HVXPOZ6dJd49xc2bEcD13tElE9byJqAMfahspmoo=; b=L//I8GHs3quf7Y/aG057X2P7qS6KFlZZDQ40c9cSren9MUiGRy9QQWIyAOc4WoPsSF 5UAkOFhbpo+mjmFa512y7lZvRgcYs/gAavBUoSPvkYAV4/uLCGSZoAMhGHf6LRLWjiv7 TQlFX7O9+5R4Z0hmFFsBZNJYUn0SrWkfg8E8RRXyA+Hpa09oxBQlnXkweUddYFsmmimm AeNAu5jJAAjhmfVk5+yfJokTPh+Q5td+AGVz25PE4xDICTHkhb69luXkjqlC3h0LpSMv dGH3lnGZl3YN/+6BipRmDi0r+RDjn1C4fF4+QmtkeFh4mlt3qdTSfUKnO4KH6Ff9nFuC DDJg== X-Gm-Message-State: APjAAAUX9eQcz4rEGTdLiIeXV14jV1QzH1a36WIl2t72H56G+LTV14aH gN4XHEFAmf/dx1Qc5oofAzzZ3critwOVPOaVluiQX0yKT+OMTGmPrMXHR29Kw55YMf/gREp0sC8 bh69MzfMqyivi/z3xFkEihtWDFzCcHla2UqoRsfNxHreLhhAlVeSNk+P0KtpqFiWMvA== X-Received: by 2002:a17:902:bb95:: with SMTP id m21mr12689115pls.154.1559081037154; Tue, 28 May 2019 15:03:57 -0700 (PDT) X-Received: by 2002:a17:902:bb95:: with SMTP id m21mr12689044pls.154.1559081036265; Tue, 28 May 2019 15:03:56 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1559081036; cv=none; d=google.com; s=arc-20160816; b=sMC9zYTv0+PpEndCGP1Vh3P2cBa/hLoITYItZDJ5tDxz8nDW+4NBOo7RO6eAkhGIe8 sB+jrlUYOg18SPQjBb/v2j+79KEQAXNydSrVi0Lt9mC3CyfmIsRyEk1DlBfR2bviRRYC xF3F06tbmwcqPYcUoHn05Wk0/rvVvNvCio+Fl7ExHltsJ8Np4ETuuUyovLr5g66YH6Wu 2jtPKzH+OXNF2bQ102QkM7lTqzodrg4jBR7kRlAbhXIVdHq/IeqkL4+HGenWg1BITAS6 BeFT10NJUhD7TJAgA5IytauPnjoBZXWwfmRpLSGva1YZXY8MjwKzLqUdL34q0iXNXsof OlKw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=ZB6HVXPOZ6dJd49xc2bEcD13tElE9byJqAMfahspmoo=; b=vrfwtQWoXzdxSQvLIcbJtoBXK26yA3qnJ8DYjskyI9MJ8OEwoPTEY+0x0T1Wsl3Foi 3NIc0g5qQk0v2/FbIucPaz1bya2G2XDxRzmcgFaVIjSnRMuGjqkMOnrXBnplJkbRzuQM e5HHz/yQFh6Q4cSuK6LMUchyNuuNG0CGPhNOs/6dIQ56HnJKgtUB9Ebr4CYCwzHPGPSX OG+YczlslKT7oGVc09ZWLqduVkN9QvCQEI1cktV0vo2cBj3zHXLZOms/H/BuZKHM9uW/ wLfUkIFpiB/BTDyfqpGKLBIDOIrlPZJUQiHS83M86q6eApe/o4pFWXLtp+GyZcR3/HLu te/A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=ToLngH1j; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id r81sor18001770pfc.59.2019.05.28.15.03.56 for (Google Transport Security); Tue, 28 May 2019 15:03:56 -0700 (PDT) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=ToLngH1j; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ZB6HVXPOZ6dJd49xc2bEcD13tElE9byJqAMfahspmoo=; b=ToLngH1jdhNI9UHTF8mqD15qUyNQONEg/Z1t3IceMNsoGy9/azm9l4mpXuBFjzeaNU DF0dDXbXAvHbBYG0zaQQPpZ/V9sOMriSfNAjQuG5jB3Z+5sMan2GbE4PmLqavh+/yWBT dBgFl+Y0x0ZlpdGRI0ttZdHXZKhRYg/Mc4cf+maDZn3pGpuX+sEs1wWdvYCtv4U6SS8v 2sZKF5aqRSTCE8fqQLDzWJzu+yMg5zVT2DhXjcFim48rFB+G6IWcYilRZeLczdJ2Jm8l iNuAb1Z6C7WuucQuNmOjutEP7zMEQcJU0AxxjHeZCcGSZVyvtBwq7unQv0RRuwvFOdlg hntQ== X-Google-Smtp-Source: APXvYqzrWHTxmX3tkqxvO2eICb8IW51vt1RCtasgNZVBi3RMlnod6+qiquwYFm4jFkcJvnbuNsMD4Q== X-Received: by 2002:a62:75c6:: with SMTP id q189mr143220121pfc.98.1559081035831; Tue, 28 May 2019 15:03:55 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::1:77ab]) by smtp.gmail.com with ESMTPSA id c97sm3674631pje.5.2019.05.28.15.03.54 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 28 May 2019 15:03:55 -0700 (PDT) Date: Tue, 28 May 2019 18:03:53 -0400 From: Johannes Weiner To: Roman Gushchin Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Michal Hocko , Rik van Riel , Shakeel Butt , Christoph Lameter , Vladimir Davydov , cgroups@vger.kernel.org, Waiman Long Subject: Re: [PATCH v5 5/7] mm: rework non-root kmem_cache lifecycle management Message-ID: <20190528220353.GC26614@cmpxchg.org> References: <20190521200735.2603003-1-guro@fb.com> <20190521200735.2603003-6-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190521200735.2603003-6-guro@fb.com> User-Agent: Mutt/1.11.4 (2019-03-13) 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, May 21, 2019 at 01:07:33PM -0700, Roman Gushchin wrote: > + arr = rcu_dereference(cachep->memcg_params.memcg_caches); > + > + /* > + * Make sure we will access the up-to-date value. The code updating > + * memcg_caches issues a write barrier to match this (see > + * memcg_create_kmem_cache()). > + */ > + memcg_cachep = READ_ONCE(arr->entries[kmemcg_id]); READ_ONCE() isn't an SMP barrier, it just prevents compiler muckery. This needs an explicit smp_rmb() to pair with the smp_wmb() on the other side. I realize you're only moving this code, but it would be good to fix that up while you're there.