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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 52BD2C43382 for ; Thu, 27 Sep 2018 12:33:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F31DB2168B for ; Thu, 27 Sep 2018 12:32:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F31DB2168B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techadventures.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727318AbeI0SvC (ORCPT ); Thu, 27 Sep 2018 14:51:02 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:56089 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727112AbeI0SvB (ORCPT ); Thu, 27 Sep 2018 14:51:01 -0400 Received: by mail-wm1-f67.google.com with SMTP id 206-v6so5726616wmb.5 for ; Thu, 27 Sep 2018 05:32:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=q4lOJ+jQdw/aWG0FNaahs6A9lQWldhauNd3wgwiV1ug=; b=YIi3F/XfTEK2maDHVW6EbZlYKIoeET6wjzP1ICqtkviQh7H3hcMUOQICh5g0dfKVA8 Y0jwBJpW/AevHyNN8X0aorrNrrMXYlWfh8kRbiozmvcZD7eR5fB0Ra/X5PGMZ8sw4Cg2 ZPSTJ5eOZ0fnTGYru9uRn01Vqy4Hf3zLk/TLWM82RGvkyA2vVQPMcoho2mX/9HYeivHh l9+7tN2RjLQ1DpfZJMWz70zfFo14YCxj+0o9cegLkMLxZkB3TDC1TKhJDcCda93NyeSz RCB1a9YsfqxbX2sNSIFnoLwcwADb0uYIjWBZQjoV8XvDPbtq3FIlxWWfcitjpZj3tQzn GXCg== X-Gm-Message-State: ABuFfoidSQ7JK4vpxNlK9Fr1s6tdXwZFVB4M0bTRRFMBpz/0/a4QMLY2 /qTLT34L8d6hUVL58lLh7CE= X-Google-Smtp-Source: ACcGV600bcs5X1VmEMzHZkh8Z847Zc+wIHZtUZ/fhWRA1YvpJSH2C35SAC0WXOXPOL6/XWlkbwg2qA== X-Received: by 2002:a1c:9295:: with SMTP id u143-v6mr1967680wmd.126.1538051575507; Thu, 27 Sep 2018 05:32:55 -0700 (PDT) Received: from techadventures.net (techadventures.net. [62.201.165.239]) by smtp.gmail.com with ESMTPSA id a1-v6sm2082587wrt.9.2018.09.27.05.32.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Sep 2018 05:32:54 -0700 (PDT) Received: by techadventures.net (Postfix, from userid 1000) id 2B78312561B; Thu, 27 Sep 2018 14:32:54 +0200 (CEST) Date: Thu, 27 Sep 2018 14:32:54 +0200 From: Oscar Salvador To: Alexander Duyck Cc: Michal Hocko , linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, pavel.tatashin@microsoft.com, dave.jiang@intel.com, dave.hansen@intel.com, jglisse@redhat.com, rppt@linux.vnet.ibm.com, dan.j.williams@intel.com, logang@deltatee.com, mingo@kernel.org, kirill.shutemov@linux.intel.com Subject: Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Message-ID: <20180927123254.GB20378@techadventures.net> References: <20180925200551.3576.18755.stgit@localhost.localdomain> <20180925202053.3576.66039.stgit@localhost.localdomain> <20180926075540.GD6278@dhcp22.suse.cz> <6f87a5d7-05e2-00f4-8568-bb3521869cea@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6f87a5d7-05e2-00f4-8568-bb3521869cea@linux.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 26, 2018 at 11:25:37AM -0700, Alexander Duyck wrote: > With that said I am open to suggestions if you still feel like I need to > follow this up with some additional work. I just want to avoid introducing > any regressions in regards to functionality or performance. Hi Alexander, the problem I see is that devm/hmm is using some of the memory-hotplug features, but their paths are becoming more and more diverged with changes like this, and that is sometimes a problem when we need to change something in the generic memory-hotplug code. E.g: I am trying to fix two issues in the memory-hotplug where we can access steal pages if we hot-remove memory before online it. That was not so difficult to fix, but I really struggled with the exceptions that HMM/devm represent in this regard, for instance, regarding the resources. The RFCv2 can be found here [1] https://patchwork.kernel.org/patch/10569083/ And the initial discussion with Jerome Glisse can be found here [2]. So it would be great to stick to the memory-hotplug path as much as possible, otherwise when a problem arises, we need to think how we can workaround HMM/devm. [1] https://patchwork.kernel.org/patch/10569083/ [2] https://patchwork.kernel.org/patch/10558725/ -- Oscar Salvador SUSE L3