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 F126EC2D0EB for ; Mon, 30 Mar 2020 08:28:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B6DAC20748 for ; Mon, 30 Mar 2020 08:28:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="EsRfzs1U" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B6DAC20748 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 6AFB06B0008; Mon, 30 Mar 2020 04:28:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 660A56B000C; Mon, 30 Mar 2020 04:28:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 574E56B0032; Mon, 30 Mar 2020 04:28:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0090.hostedemail.com [216.40.44.90]) by kanga.kvack.org (Postfix) with ESMTP id 3DA646B0008 for ; Mon, 30 Mar 2020 04:28:21 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id DE3AB181AD0A5 for ; Mon, 30 Mar 2020 08:28:20 +0000 (UTC) X-FDA: 76651351560.10.vase91_830bffc86d04a X-HE-Tag: vase91_830bffc86d04a X-Filterd-Recvd-Size: 5987 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [63.128.21.74]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Mar 2020 08:28:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585556900; 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=urh/QqSLIbmDRa1+bqKhLnHsVy5DBePTPVKLtVq9St4=; b=EsRfzs1UbRRzzHvzCDBR89TFxK7WB3SI4kr0K9y0skyFMYSEis/3ocFbANRwy/GK87HzHt 8WWbyFPLLAsn/pb2x2F4+xUS24i4wAgBSqXgRo7D5DrtSjIzqTV1dApOdX2BEtOxBHvhF2 2tbDkBPQphbulHDcfX3UJrQnfFd2sPI= 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-472-SBmE0C2qM4iblPlKXUQf2w-1; Mon, 30 Mar 2020 04:28:18 -0400 X-MC-Unique: SBmE0C2qM4iblPlKXUQf2w-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 9A90F18CA243; Mon, 30 Mar 2020 08:28:14 +0000 (UTC) Received: from localhost (ovpn-12-53.pek2.redhat.com [10.72.12.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4451B100EBAF; Mon, 30 Mar 2020 08:28:13 +0000 (UTC) Date: Mon, 30 Mar 2020 16:28:09 +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: <20200330082809.GB6352@MiWiFi-R3L-srv> References: <1585420282-25630-1-git-send-email-Hoan@os.amperecomputing.com> <20200330074246.GA14243@dhcp22.suse.cz> <20200330081659.GA6352@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200330081659.GA6352@MiWiFi-R3L-srv> 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 04:16pm, Baoquan He wrote: > 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. Ok, I didn't read code carefully. That is handling case where memblock with different node id overlap, it needs return. In the example Hoan gave, it has no problem, system can run well. Please ignore above comment.