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=-1.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D2EA1C43331 for ; Mon, 30 Mar 2020 18:23:08 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A9ED2206F6 for ; Mon, 30 Mar 2020 18:23:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tGQ5uJyg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9ED2206F6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=XH9Iz6dhqG8BK2BxU922nMQIC6sVxsIqMH2/lqC5uww=; b=tGQ5uJygy6URxJ DTQo1EDPDpMNU2kpfaF89EVhC/ivPrKVlAOzVQl0jDMWThvoht57vENJaGuthB86+nlvw+2ctg4dQ 7bi6bPCwipDgZVmaNsDiv5s1N0Ywcd5EdLXHy14IDUXWojV9RmtklAK7kmP3ek20lRLsdZ5PlQx/H 5A/vikEpN6T7BTzrJvVyFFakEvj1BM9xgBuqWVcvJYAZZE6QmfALn6b2i4LcdQ+y9Yz8BMv6R6SPC oDf3PQvAGyWRKaeE2F87vfJJFi1rPAerwSGITxiIK3EDFZzqGJ+HZ/3OI/UCoN2Zy5S40pdlX2MSV CuHaVUGJoo20xdQ945NA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jIz3z-0003uT-OH; Mon, 30 Mar 2020 18:23:07 +0000 Received: from mail-wr1-f66.google.com ([209.85.221.66]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jIz3w-0003rL-MN for linux-arm-kernel@lists.infradead.org; Mon, 30 Mar 2020 18:23:06 +0000 Received: by mail-wr1-f66.google.com with SMTP id a25so22951712wrd.0 for ; Mon, 30 Mar 2020 11:23:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=0jhRFYVkza+qJU3Il8/iXGVhPGBzX8dkXPD9i1bwSag=; b=ivA14OmGxELXw3INOvHFdnkBOOLRjqgMBJstXMt3+kvgfEmCZ2+dzPljVe7nu1CWxd Pw91ZbNv3EiiUbzTak02hBjPcYq7rfrk0oEPSDn/9JQGJAw6Mc54eFYs9PbcSWUGvz8/ orl4rMfN3pjiLAfKWLI5hvvLLx5vJBErDiCxZ1RHzvkWKv5eqCT87hBJruWq4TN8Iy85 NwMIPI2uNynosOdpapryQaU0SVmukJnRJfGfAFO1DgwFBO1Z5+AM/eetaZVPxtiCKpHx l9aOLCSHDAD6Zs2vYeLCL9vWYIAjaoRmgmOP90ApSfbzQaw5deucRFqtkEcdDEjwxmdI 3CbA== X-Gm-Message-State: ANhLgQ3icHUCqGWptirXHy4qc6f1RRvkSN9rUjc+B+vD+0gbJ9cIszLS BxSPe+4leSF9lLjrECkPrU8= X-Google-Smtp-Source: ADFU+vv5K/FBYjKeTVX0F/L19lDVfm50dWVM5MaRN4MeyMqOqGnWTdxnNM7cmfvlZTzDum9SAd0OPg== X-Received: by 2002:adf:d849:: with SMTP id k9mr15996160wrl.108.1585592583199; Mon, 30 Mar 2020 11:23:03 -0700 (PDT) Received: from localhost (ip-37-188-180-223.eurotel.cz. [37.188.180.223]) by smtp.gmail.com with ESMTPSA id f187sm474696wme.9.2020.03.30.11.23.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2020 11:23:02 -0700 (PDT) Date: Mon, 30 Mar 2020 20:23:01 +0200 From: Michal Hocko To: Mike Rapoport Subject: Re: [PATCH v3 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA Message-ID: <20200330182301.GM14243@dhcp22.suse.cz> References: <1585420282-25630-1-git-send-email-Hoan@os.amperecomputing.com> <20200330074246.GA14243@dhcp22.suse.cz> <20200330175100.GD30942@linux.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200330175100.GD30942@linux.ibm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200330_112304_732339_D8124ED8 X-CRM114-Status: GOOD ( 25.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mmorana@amperecomputing.com, Catalin Marinas , Heiko Carstens , "open list:MEMORY MANAGEMENT" , Paul Mackerras , "H. Peter Anvin" , sparclinux@vger.kernel.org, Alexander Duyck , linux-s390@vger.kernel.org, Michael Ellerman , x86@kernel.org, Christian Borntraeger , Ingo Molnar , Hoan Tran , Benjamin Herrenschmidt , Pavel Tatashin , lho@amperecomputing.com, Vasily Gorbik , Vlastimil Babka , Will Deacon , Borislav Petkov , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Oscar Salvador , linux-kernel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon 30-03-20 20:51:00, Mike Rapoport wrote: > On Mon, Mar 30, 2020 at 09:42:46AM +0200, 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. > > I've looked at this a bit more and it seems that the check for > early_pfn_in_nid() in memmap_init_zone() can be simply removed. > > The commits you've mentioned were way before the addition of > HAVE_MEMBLOCK_NODE_MAP and the whole infrastructure that calculates zone > sizes and boundaries based on the memblock node map. > So, the memmap_init_zone() is called when zone boundaries are already > within a node. But zones from different nodes might overlap in the pfn range. And this check is there to skip over those overlapping areas. The only way to skip over this check I can see is to do a different pfn walk and go through memblock ranges which are guaranteed to belong to a single node. -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel