Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82A96C433FE for ; Tue, 7 Dec 2021 15:56:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239253AbhLGP7q (ORCPT ); Tue, 7 Dec 2021 10:59:46 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:46648 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229879AbhLGP7p (ORCPT ); Tue, 7 Dec 2021 10:59:45 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 8889D1FE00; Tue, 7 Dec 2021 15:56:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1638892574; h=from:from:reply-to: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=eIuuu/kOGy1zuDG2ON0nQADHm6iD+deyHDd0QC8WGMg=; b=hsdS34/zBKzEB0fwf/afqKYsPcTbONTw7GkyZJZkt8cVDZWyG2z4m1m1LkdGqu2aY9HAnQ DlQKS3WRGGKKr98FP4rWbEIQy6HI/HuJiH43nEFcvhqYxMBCROyQ2rLQCGmEM8m2cv2/Vu +w+EOQ8EtasCyB4TgnKwyT3SPHcREYI= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 58562A3B85; Tue, 7 Dec 2021 15:56:14 +0000 (UTC) Date: Tue, 7 Dec 2021 16:56:13 +0100 From: Michal Hocko To: David Hildenbrand Cc: Alexey Makhalov , Dennis Zhou , Eric Dumazet , "linux-mm@kvack.org" , Andrew Morton , Oscar Salvador , Tejun Heo , Christoph Lameter , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH v3] mm: fix panic in __alloc_pages Message-ID: References: <5239D699-523C-4F0C-923A-B068E476043E@vmware.com> <1043a1a4-b7f2-8730-d192-7cab9f15ee24@redhat.com> <77e785e6-cf34-0cff-26a5-852d3786a9b8@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 07-12-21 16:34:30, David Hildenbrand wrote: > On 07.12.21 16:29, Michal Hocko wrote: > > On Tue 07-12-21 16:09:39, David Hildenbrand wrote: > >> On 07.12.21 14:23, Michal Hocko wrote: > >>> On Tue 07-12-21 13:28:31, David Hildenbrand wrote: > >>> [...] > >>>> But maybe I am missing something important regarding online vs. offline > >>>> nodes that your patch changes? > >>> > >>> I am relying on alloc_node_data setting the node online. But if we are > >>> to change the call to arch_alloc_node_data then the patch needs to be > >>> more involved. Here is what I have right now. If this happens to be the > >>> right way then there is some additional work to sync up with the hotplug > >>> code. > >>> > >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >>> index c5952749ad40..a296e934ad2f 100644 > >>> --- a/mm/page_alloc.c > >>> +++ b/mm/page_alloc.c > >>> @@ -8032,8 +8032,23 @@ void __init free_area_init(unsigned long *max_zone_pfn) > >>> /* Initialise every node */ > >>> mminit_verify_pageflags_layout(); > >>> setup_nr_node_ids(); > >>> - for_each_online_node(nid) { > >>> - pg_data_t *pgdat = NODE_DATA(nid); > >>> + for_each_node(nid) { > >>> + pg_data_t *pgdat; > >>> + > >>> + if (!node_online(nid)) { > >>> + pr_warn("Node %d uninitialized by the platform. Please report with memory map.\n", nid); > >>> + pgdat = arch_alloc_nodedata(nid); > >>> + pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat); > >>> + arch_refresh_nodedata(nid, pgdat); > >>> + node_set_online(nid); > >> > >> Setting all possible nodes online might result in quite some QE noice, > >> because all these nodes will then be visible in the sysfs and > >> try_offline_nodes() is essentially for the trash. > > > > I am not sure I follow. I believe sysfs will not get populate because I > > do not call register_one_node. > > arch/x86/kernel/topology.c:topology_init() > > for_each_online_node(i) > register_one_node(i); Right you are. > > You are right that try_offline_nodes will be reduce which is good imho. > > More changes will be possible (hopefully to drop some ugly code) on top > > of this change (or any other that achieves that there are no NULL pgdat > > for possible nodes). > > > > No to exposing actually offline nodes to user space via sysfs. Why is that a problem with the sysfs for non-populated nodes? -- Michal Hocko SUSE Labs