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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 52DB9C432C0 for ; Thu, 28 Nov 2019 11:23:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DD40A21741 for ; Thu, 28 Nov 2019 11:23:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PEPZhSOk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD40A21741 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 55D846B051D; Thu, 28 Nov 2019 06:23:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4E6216B051E; Thu, 28 Nov 2019 06:23:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3882C6B051F; Thu, 28 Nov 2019 06:23:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id 1FF146B051D for ; Thu, 28 Nov 2019 06:23:18 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id A5C9F4995EE for ; Thu, 28 Nov 2019 11:23:17 +0000 (UTC) X-FDA: 76205450034.21.ants83_1c9837f186346 X-HE-Tag: ants83_1c9837f186346 X-Filterd-Recvd-Size: 10135 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Nov 2019 11:23:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574940195; 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=aGoVj5If+G1SY0s+s1S/adEuG3SMz1NIzlDkSDuLvRs=; b=PEPZhSOka6tg8IuKEjUYBWDO/LU2v7TYz3jai22DITBgja6s4HWt5XXWbxx94P4lhoJUY8 RAXY+vds6xVXiznv8kqHqAiHbeqLaFm+DcFZaKqbQDET5SgZRD3MLHEXCE9p9UoiD5YdvI 3hFuvqLdWHuSDizWTbZMtchE8DOmDY4= 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-264-vJKzzGPfM6eHCC3LxifiOA-1; Thu, 28 Nov 2019 06:23:12 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AE0A01005510; Thu, 28 Nov 2019 11:23:10 +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 054C3600C8; Thu, 28 Nov 2019 11:23:08 +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> 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: Date: Thu, 28 Nov 2019 12:23:08 +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: <5E2F5866-0605-4DD2-9AEA-4B1C44E57D9F@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: vJKzzGPfM6eHCC3LxifiOA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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 11:25, David Hildenbrand wrote: >=20 >=20 >> Am 28.11.2019 um 11:20 schrieb Michal Hocko : >> >> =EF=BB=BFOn Wed 27-11-19 18:41:26, David Hildenbrand wrote: >>> Since commit d84f2f5a7552 ("drivers/base/node.c: simplify >>> unregister_memory_block_under_nodes()") we only have a single user of >>> get_nid_for_pfn(). Let's just inline that code and get rid of >>> get_nid_for_pfn(). >>> >>> Cc: Greg Kroah-Hartman >>> Cc: "Rafael J. Wysocki" >>> Cc: Michal Hocko >>> Cc: Oscar Salvador >>> Cc: Andrew Morton >>> Signed-off-by: David Hildenbrand >> >> I am not really sure this is an improvement. The code is ugly as hell >> and open coding it just makes register_mem_sect_under_node harder to >> read. >=20 > The issue I see is that this is a dangerous wrapper for pfn_to_nid() that= is absolutely not obvious. The old second user on the memory removal path = was completely buggy. IMHO nobody should be reusing that function. But it l= ooks like a general =E2=80=9Esafe wrapper to get a nid=E2=80=9C - it=E2=80= =98s not. >=20 > How can we make that more obvious instead? >=20 What about something like this (untested): >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 >=3D 0). Cc: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Cc: Michal Hocko Cc: Oscar Salvador Cc: Andrew Morton Signed-off-by: David Hildenbrand --- drivers/base/node.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/drivers/base/node.c b/drivers/base/node.c index 98a31bafc8a2..d525e30581de 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -744,14 +744,16 @@ int unregister_cpu_under_node(unsigned int cpu, unsig= ned int nid) } =20 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE -static int __ref get_nid_for_pfn(unsigned long pfn) +static int __ref boot_pfn_to_nid(unsigned long pfn) { =09if (!pfn_valid_within(pfn)) =09=09return -1; -#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT -=09if (system_state < SYSTEM_RUNNING) +=09/* +=09 * With deferred struct page initialization, the memmap will contain +=09 * garbage - we have to rely on the early nid. +=09 */ +=09if (IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) =09=09return early_pfn_to_nid(pfn); -#endif =09return pfn_to_nid(pfn); } =20 @@ -766,8 +768,6 @@ static int register_mem_sect_under_node(struct memory_b= lock *mem_blk, =09unsigned long pfn; =20 =09for (pfn =3D start_pfn; pfn <=3D end_pfn; pfn++) { -=09=09int page_nid; - =09=09/* =09=09 * memory block could have several absent sections from start. =09=09 * skip pfn range from absent section @@ -783,13 +783,9 @@ static int register_mem_sect_under_node(struct memory_= block *mem_blk, =09=09 * case, during hotplug we know that all pages in the memory =09=09 * block belong to the same node. =09=09 */ -=09=09if (system_state =3D=3D SYSTEM_BOOTING) { -=09=09=09page_nid =3D get_nid_for_pfn(pfn); -=09=09=09if (page_nid < 0) -=09=09=09=09continue; -=09=09=09if (page_nid !=3D nid) -=09=09=09=09continue; -=09=09} +=09=09if (system_state =3D=3D SYSTEM_BOOTING && +=09=09 boot_pfn_to_nid(pfn) !=3D nid) +=09=09=09continue; =20 =09=09/* =09=09 * If this memory block spans multiple nodes, we only indicate --=20 2.21.0 --=20 Thanks, David / dhildenb