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 89CBDC433EF for ; Wed, 8 Dec 2021 08:12:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244690AbhLHIQC (ORCPT ); Wed, 8 Dec 2021 03:16:02 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:43498 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244682AbhLHIP5 (ORCPT ); Wed, 8 Dec 2021 03:15:57 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id AC64F2190C; Wed, 8 Dec 2021 08:12:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1638951143; 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=EqPRBZg91RMq41owz+XvEfa3k4OtiHy0sHFbutmVHzQ=; b=gdHURKuUPwiBpBFl+lD9+bX30gLnE+tgp/QZtUmE1aFil5NLjMMFrR4wM3p4WS6+5gSfCs C5/mdHAvTOIeaf4SxV9HCsUcwPW1emS87THiZ11Zp1t7PG2myd9qNDWuwk4W5S4cKJTIQq U01WTK2NBjnUNXwNZZkZDd5y9q87MlQ= 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 67671A3B81; Wed, 8 Dec 2021 08:12:23 +0000 (UTC) Date: Wed, 8 Dec 2021 09:12:22 +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: <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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 07-12-21 19:03:28, David Hildenbrand wrote: > On 07.12.21 18:17, 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) > > I thought the pgdat would be smaller but I just gave it a test: Yes, pgdat is quite large! Just embeded zones can eat a lot. > On my system, pgdata_t is 173824 bytes. So 128 nodes would correspond to > 21 MiB, which is indeed a lot. I assume it's due to "struct zonelist", > which has MAX_ZONES_PER_ZONELIST == (MAX_NUMNODES * MAX_NR_ZONES) zone > references ... This is what pahole tells me struct pglist_data { struct zone node_zones[4] __attribute__((__aligned__(64))); /* 0 5632 */ /* --- cacheline 88 boundary (5632 bytes) --- */ struct zonelist node_zonelists[1]; /* 5632 80 */ [...] /* size: 6400, cachelines: 100, members: 27 */ /* sum members: 6369, holes: 5, sum holes: 31 */ with my particular config (which is !NUMA). I haven't really checked whether there are other places which might scale with MAX_NUM_NODES or something like that. Anyway, is 21MB of wasted space for 128 Node machine something really note worthy? -- Michal Hocko SUSE Labs