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 0B64DC2D0EB for ; Mon, 30 Mar 2020 08:17:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C45F520757 for ; Mon, 30 Mar 2020 08:17:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CP+s9T+T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729625AbgC3IRM (ORCPT ); Mon, 30 Mar 2020 04:17:12 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:52359 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729589AbgC3IRM (ORCPT ); Mon, 30 Mar 2020 04:17:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585556231; 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=q5ngBcPb7bElTSwNqwk2fMuVOgMr6WDANdu6wvSJ458=; b=CP+s9T+TGeMa5oLD7GuIKullUAY4B6E8thNA/mm1eMkr9/dAkV/2LH5XGZN2suSTbXnxPY pT/4KbEqtju2f5QcEEVrYHBU5UFH7EFjJEMsI4KBTC1jzEfBij1JOIwWdcqHk8Nbl5Ytw9 paTCmfXEDNyiCiMQtyRh9281wHheY9M= 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-321-VZIKPOA2PLCKJ81-Hi2ZBg-1; Mon, 30 Mar 2020 04:17:07 -0400 X-MC-Unique: VZIKPOA2PLCKJ81-Hi2ZBg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F0FE8017CC; Mon, 30 Mar 2020 08:17:03 +0000 (UTC) Received: from localhost (ovpn-12-53.pek2.redhat.com [10.72.12.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0DFFF19925; Mon, 30 Mar 2020 08:17:02 +0000 (UTC) Date: Mon, 30 Mar 2020 16:16:59 +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: <20200330081659.GA6352@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 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Yeah, since early_pfnnid_cache was added, we do not need worry about the performance. But when I read the mem init code on x86 again, I do see there are codes to handle the node overlapping, e.g in numa_cleanup_meminfo(), when store node id into memblock. But the thing is if we have encountered the node overlapping, we just return ahead of time, leave something uninitialized. I am wondering if the system with node overlapping can still run heathily. > > > 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 >