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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1BDBBC43331 for ; Mon, 30 Mar 2020 09:26:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D61C6206F6 for ; Mon, 30 Mar 2020 09:26:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ByEYRusV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D61C6206F6 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 6D1BC6B0008; Mon, 30 Mar 2020 05:26:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A8D06B000C; Mon, 30 Mar 2020 05:26:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5BEA16B0032; Mon, 30 Mar 2020 05:26:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0196.hostedemail.com [216.40.44.196]) by kanga.kvack.org (Postfix) with ESMTP id 4333E6B0008 for ; Mon, 30 Mar 2020 05:26:18 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 048ED180AD806 for ; Mon, 30 Mar 2020 09:26:18 +0000 (UTC) X-FDA: 76651497636.15.sail48_36f4b5b2eff14 X-HE-Tag: sail48_36f4b5b2eff14 X-Filterd-Recvd-Size: 6390 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [63.128.21.74]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Mar 2020 09:26:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585560377; 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: in-reply-to:in-reply-to:references:references; bh=P7KONnLRBt7Zi6IX/bJ2rtifHakTT+zqNud06VP531U=; b=ByEYRusVLs3NWG4WNPMWE7dVfN2uyuWqOvh03tk4DBTiYZLGnE2eaiw+DT0deREIN6nSED 0rs5YyAraUaExouH5W34GZ4yiOuWw0/dEuDw/MguMew5b+hu0+4AMISqelCqjnpJamtjAa N5fSMHdi/N+OJPMiAAeBwb/+WxL/qfU= 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-348-v6Tx4dfaPXm-1wc0_ZqlsA-1; Mon, 30 Mar 2020 05:26:14 -0400 X-MC-Unique: v6Tx4dfaPXm-1wc0_ZqlsA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E4A2518A552A; Mon, 30 Mar 2020 09:26:10 +0000 (UTC) Received: from localhost (ovpn-12-53.pek2.redhat.com [10.72.12.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A853510027AA; Mon, 30 Mar 2020 09:26:09 +0000 (UTC) Date: Mon, 30 Mar 2020 17:26:06 +0800 From: Baoquan He To: Michal Hocko Cc: Hoan Tran , Catalin Marinas , Will Deacon , Andrew Morton , Vlastimil Babka , Oscar Salvador , Pavel Tatashin , Mike Rapoport , Alexander Duyck , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "David S. Miller" , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , "open list:MEMORY MANAGEMENT" , linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, lho@amperecomputing.com, mmorana@amperecomputing.com Subject: Re: [PATCH v3 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA Message-ID: <20200330092606.GC6352@MiWiFi-R3L-srv> References: <1585420282-25630-1-git-send-email-Hoan@os.amperecomputing.com> <20200330074246.GA14243@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200330074246.GA14243@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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 03/30/20 at 09:42am, Michal Hocko wrote: > On Sat 28-03-20 11:31:17, Hoan Tran wrote: > > In NUMA layout which nodes have memory ranges that span across other nodes, > > the mm driver can detect the memory node id incorrectly. > > > > For example, with layout below > > Node 0 address: 0000 xxxx 0000 xxxx > > Node 1 address: xxxx 1111 xxxx 1111 > > > > Note: > > - Memory from low to high > > - 0/1: Node id > > - x: Invalid memory of a node > > > > When mm probes the memory map, without CONFIG_NODES_SPAN_OTHER_NODES > > config, mm only checks the memory validity but not the node id. > > Because of that, Node 1 also detects the memory from node 0 as below > > when it scans from the start address to the end address of node 1. > > > > Node 0 address: 0000 xxxx xxxx xxxx > > Node 1 address: xxxx 1111 1111 1111 > > > > This layout could occur on any architecture. Most of them enables > > this config by default with CONFIG_NUMA. This patch, by default, enables > > CONFIG_NODES_SPAN_OTHER_NODES or uses early_pfn_in_nid() for NUMA. > > I am not opposed to this at all. It reduces the config space and that is > a good thing on its own. The history has shown that meory layout might > be really wild wrt NUMA. The config is only used for early_pfn_in_nid > which is clearly an overkill. > > Your description doesn't really explain why this is safe though. The > history of this config is somehow messy, though. Mike has tried > to remove it a94b3ab7eab4 ("[PATCH] mm: remove arch independent > NODES_SPAN_OTHER_NODES") just to be reintroduced by 7516795739bd > ("[PATCH] Reintroduce NODES_SPAN_OTHER_NODES for powerpc") without any > reasoning what so ever. This doesn't make it really easy see whether > reasons for reintroduction are still there. Maybe there are some subtle > dependencies. I do not see any TBH but that might be burried deep in an > arch specific code. Since on all ARCHes NODES_SPAN_OTHER_NODES has dependency on NUMA, replacing it with CONFIG_NUMA seems no risk. Just for those ARCHes which don't have CONFIG_NODES_SPAN_OTHER_NODES before, it involves a tiny performance degradation. Besides, s390 has removed support of NODES_SPAN_OTHER_NODES already. commit 701dc81e7412daaf3c5bf4bc55d35c8b1525112a Author: Heiko Carstens Date: Wed Feb 19 13:29:15 2020 +0100 s390/mm: remove fake numa support > > > v3: > > * Revise the patch description > > > > V2: > > * Revise the patch description > > > > Hoan Tran (5): > > mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA > > powerpc: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES > > x86: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES > > sparc: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES > > s390: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES > > > > arch/powerpc/Kconfig | 9 --------- > > arch/s390/Kconfig | 8 -------- > > arch/sparc/Kconfig | 9 --------- > > arch/x86/Kconfig | 9 --------- > > mm/page_alloc.c | 2 +- > > 5 files changed, 1 insertion(+), 36 deletions(-) > > > > -- > > 1.8.3.1 > > > > -- > Michal Hocko > SUSE Labs >