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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B042C433FE for ; Wed, 8 Dec 2021 08:04:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244645AbhLHIH5 (ORCPT ); Wed, 8 Dec 2021 03:07:57 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:38946 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240425AbhLHIH4 (ORCPT ); Wed, 8 Dec 2021 03:07:56 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 05AEE1FDFC; Wed, 8 Dec 2021 08:04:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1638950664; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WMGjw44+jXQO3zu5GwYDCF7IsnMd3YaPPro0gBCKQtc=; b=oXoYxxNDCEl899Jtek3M9lpNe1PAAXNc4D6+9gNPWpJ00vzAefmFwbXHgKPaeMXKyutVdx nGhgvijtZ+SnWPNmkjCVUVgzeFXMf5I4yVmv77AgtZ08U0moj1dpHrJp7EY1QbSLNphxy2 4uS0IW4tm29TIJRXdOwWgMy++8zu/OU= 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 C655DA3B85; Wed, 8 Dec 2021 08:04:23 +0000 (UTC) Date: Wed, 8 Dec 2021 09:04:21 +0100 From: Michal Hocko To: Alexey Makhalov Cc: David Hildenbrand , 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: <77e785e6-cf34-0cff-26a5-852d3786a9b8@redhat.com> <2E174230-04F3-4798-86D5-1257859FFAD8@vmware.com> <21539fc8-15a8-1c8c-4a4f-8b85734d2a0e@redhat.com> <78E39A43-D094-4706-B4BD-18C0B18EB2C3@vmware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <78E39A43-D094-4706-B4BD-18C0B18EB2C3@vmware.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 07-12-21 17:17:27, Alexey Makhalov wrote: > > > > On Dec 7, 2021, at 9:13 AM, David Hildenbrand wrote: > > > > On 07.12.21 18:02, Alexey Makhalov wrote: > >> > >> > >>> On Dec 7, 2021, at 8:36 AM, Michal Hocko wrote: > >>> > >>> On Tue 07-12-21 17:27:29, Michal Hocko wrote: > >>> [...] > >>>> So your proposal is to drop set_node_online from the patch and add it as > >>>> a separate one which handles > >>>> - sysfs part (i.e. do not register a node which doesn't span a > >>>> physical address space) > >>>> - hotplug side of (drop the pgd allocation, register node lazily > >>>> when a first memblocks are registered) > >>> > >>> In other words, the first stage > >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >>> index c5952749ad40..f9024ba09c53 100644 > >>> --- a/mm/page_alloc.c > >>> +++ b/mm/page_alloc.c > >>> @@ -6382,7 +6382,11 @@ static void __build_all_zonelists(void *data) > >>> if (self && !node_online(self->node_id)) { > >>> build_zonelists(self); > >>> } else { > >>> - for_each_online_node(nid) { > >>> + /* > >>> + * All possible nodes have pgdat preallocated > >>> + * free_area_init > >>> + */ > >>> + for_each_node(nid) { > >>> pg_data_t *pgdat = NODE_DATA(nid); > >>> > >>> build_zonelists(pgdat); > >> > >> Will it blow up memory usage for the nodes which might never be onlined? > >> I prefer the idea of init on demand. > >> > >> Even now there is an existing problem. > >> In my experiments, I observed _huge_ memory consumption increase by increasing number > >> of possible numa nodes. I’m going to report it in separate mail thread. > > > > I already raised that PPC might be problematic in that regard. Which > > architecture / setup do you have in mind that can have a lot of possible > > nodes? > > > It is x86_64 VMware VM, not the regular one, but specially configured (1 vCPU per node, > with hot-plug support, 128 possible nodes) This is slightly tangent but could you elaborate more on this setup and reasoning behind it. I was already curious when you mentioned this previously. Why would you want to have so many nodes and having 1:1 with CPUs. What is the resulting NUMA topology? -- Michal Hocko SUSE Labs