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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 5B8B6C432C0 for ; Thu, 28 Nov 2019 12:19:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1602B217AB for ; Thu, 28 Nov 2019 12:19:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WnHzb3M6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1602B217AB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BC10E6B0527; Thu, 28 Nov 2019 07:19:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B71E46B0528; Thu, 28 Nov 2019 07:19:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A61AD6B0529; Thu, 28 Nov 2019 07:19:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0046.hostedemail.com [216.40.44.46]) by kanga.kvack.org (Postfix) with ESMTP id 903B06B0527 for ; Thu, 28 Nov 2019 07:19:37 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 3CA86180AD807 for ; Thu, 28 Nov 2019 12:19:37 +0000 (UTC) X-FDA: 76205591994.06.egg15_53c5e02d21726 X-HE-Tag: egg15_53c5e02d21726 X-Filterd-Recvd-Size: 8776 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by imf27.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Nov 2019 12:19:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574943574; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=LeQTYn9Qt3o5rA+WQNAxKHbZ5MgiJd0v7EjtKEdo+zI=; b=WnHzb3M6GpIs6b6tFN8IifCEHGqZX5WwZxBIUnRAlwR9IkaEJCX48vESBXompnjEH3BHDG QtIP4pTlRr7tXeen/CnHaEa/Rn/3cHw5aFnKm8kJLj7N5JScJez99ql2R0pV86VfNj8yrd g5TvMP0D9U5jmQdn6jyn08n69hguTvc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-149-blxf5S4uOSaEd2bEQRehxQ-1; Thu, 28 Nov 2019 07:19:31 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8182C800D4C; Thu, 28 Nov 2019 12:19:29 +0000 (UTC) Received: from [10.36.116.124] (ovpn-116-124.ams2.redhat.com [10.36.116.124]) by smtp.corp.redhat.com (Postfix) with ESMTP id DC0205D6C8; Thu, 28 Nov 2019 12:19:27 +0000 (UTC) Subject: Re: [PATCH v1] drivers/base/node.c: get rid of get_nid_for_pfn() To: Michal Hocko Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Oscar Salvador , Andrew Morton References: <20191128102051.GI26807@dhcp22.suse.cz> <5E2F5866-0605-4DD2-9AEA-4B1C44E57D9F@redhat.com> <20191128115021.GJ26807@dhcp22.suse.cz> <20191128120121.GL26807@dhcp22.suse.cz> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAj4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+uQINBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABiQIl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <17785662-d004-21ad-16a6-296c82779c8f@redhat.com> Date: Thu, 28 Nov 2019 13:19:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191128120121.GL26807@dhcp22.suse.cz> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: blxf5S4uOSaEd2bEQRehxQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit 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 28.11.19 13:01, Michal Hocko wrote: > On Thu 28-11-19 12:52:16, David Hildenbrand wrote: >> On 28.11.19 12:50, Michal Hocko wrote: >>> On Thu 28-11-19 12:23:08, David Hildenbrand wrote: >>> [...] >>>> >From fc13fd540a1702592e389e821f6266098e41e2bd Mon Sep 17 00:00:00 2001 >>>> From: David Hildenbrand >>>> Date: Wed, 27 Nov 2019 16:18:42 +0100 >>>> Subject: [PATCH] drivers/base/node.c: optimize get_nid_for_pfn() >>>> >>>> Since commit d84f2f5a7552 ("drivers/base/node.c: simplify >>>> unregister_memory_block_under_nodes()") we only have a single user of >>>> get_nid_for_pfn(). The remaining user calls this function when booting - >>>> where all added memory is online. >>>> >>>> Make it clearer that this function should only be used during boot ( >>>> e.g., calling it on offline memory would be bad) by renaming the >>>> function to something meaningful, optimize out the ifdef and the additional >>>> system_state check, and add a comment why CONFIG_DEFERRED_STRUCT_PAGE_INIT >>>> handling is in place at all. >>>> >>>> Also, optimize the call site. There is no need to check against >>>> page_nid < 0 - it will never match the nid (nid >= 0). >>>> >>>> Cc: Greg Kroah-Hartman >>>> Cc: "Rafael J. Wysocki" >>>> Cc: Michal Hocko >>>> Cc: Oscar Salvador >>>> Cc: Andrew Morton >>>> Signed-off-by: David Hildenbrand >>> >>> Yes this looks much better! I am not sure this will pass all weird >>> config combinations because IS_ENABLED will not hide early_pfn_to_nid >>> from the early compiler stages so it might complain. But if this passes >>> 0day compile scrutiny then this is much much better. If not then we just >>> have to use ifdef which is a minor thing. >> >> The compiler should optimize out >> >> if (0) >> code >> >> and therefore never link to early_pfn_to_nid. > > You are right, but there is a catch. The optimization phase is much > later than the syntactic check so if the code doesn't make sense > for the syntactic point of view then it will complain. This is a notable > difference to #ifdef which just removes the whole block in the > preprocessor phase. > We should always have a declaration of early_pfn_to_nid(). The interesting part AFAIKS is include/linux/mmzone.h: #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \ !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) static inline unsigned long early_pfn_to_nid(unsigned long pfn) { BUILD_BUG_ON(IS_ENABLED(CONFIG_NUMA)); return 0; } #endif so we would have if (IS_ENABLED(...)) BUILD_BUG_ON(IS_ENABLED(CONFIG_NUMA)); Let's see how that will turn out :) Will do some test builds (CONFIG_NUMA, !CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID and !CONFIG_HAVE_MEMBLOCK_NODE_MAP) ... if possible -- Thanks, David / dhildenb