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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E88BEC636D4 for ; Wed, 15 Feb 2023 09:42:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 856E16B0073; Wed, 15 Feb 2023 04:42:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 807656B0074; Wed, 15 Feb 2023 04:42:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6A7D36B0075; Wed, 15 Feb 2023 04:42:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 544A26B0073 for ; Wed, 15 Feb 2023 04:42:08 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 121B81C6C61 for ; Wed, 15 Feb 2023 09:42:08 +0000 (UTC) X-FDA: 80469035136.10.C1309FB Received: from mail-pj1-f41.google.com (mail-pj1-f41.google.com [209.85.216.41]) by imf12.hostedemail.com (Postfix) with ESMTP id E292540002 for ; Wed, 15 Feb 2023 09:42:04 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=yNsyUfoC; spf=pass (imf12.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.216.41 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676454125; h=from:from:sender:reply-to:subject:subject: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:dkim-signature; bh=iqBlTSVugTjnyCrRiAgqEdfXQROVguekXI86WbF+IXs=; b=JBR7YG6tf9GKj7Ln+hZf5mmCS+c5cM8jIhPnJS/Tm9H1bDhgNm2kiVLch1DFfHC8b4A8CM vLkM98Mit3UcrzXA/HcgP3r6zax3wVYlUsVvRiwGY7mu9+vudJC2zJ8D0j5A8OnG9CCFT9 p+fS47+rEtQjGsUwwN50i9ky2nEaodM= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=yNsyUfoC; spf=pass (imf12.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.216.41 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676454125; a=rsa-sha256; cv=none; b=X6C5alm3Pe0TdTPHItNyaQGF3t4IrRqYw9MqowfMiGaWAfRddgF/+NRNOVqUX4TdNqqos4 auuHRnYyh0Gfw3qzBGAyypUKR3/cPtdR6TFkIoO9jvTgNzKZfDxpafSMW66zWzqnKKvAIc xXuBBOnng1g6U9x4oc8V2QiX3gR8q7Y= Received: by mail-pj1-f41.google.com with SMTP id oa11-20020a17090b1bcb00b002341a2656e5so1380116pjb.1 for ; Wed, 15 Feb 2023 01:42:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=iqBlTSVugTjnyCrRiAgqEdfXQROVguekXI86WbF+IXs=; b=yNsyUfoCLWT9tBEhOmVEAUvo6VRTOIzHHniVqoX/eXQLQXCjYE6yUlw0YESaYJ3g+U eI4yw1Zia4vm5W7d/k2NHMWN5RFvqIyzpR4dHfg2gbYX9HHjc24GPOtuLDoNdMMMPiog sXVY9tP7IE/igBC0fCPa0QZOLxqJtRKKfFD/DqkK/zAMZeliB+Ez5iC2uH7z5vZw4vsA ziwMBEhUfPRfWp5SsQoCgVnKZ2wSyHxZJJaL23cGXS+r+SqzUMmoysK2XI73wIfcylBV 1xPCjuqOfHyxo+yO8+cpwHySuR53+I0BPO+f48sEAaZX5L/ToCrnA/HmkwQ1znjvfjBP x4Hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=iqBlTSVugTjnyCrRiAgqEdfXQROVguekXI86WbF+IXs=; b=vR44rnM1t0QY/v4Xgc7dmQsWGJJXAFPeeY9UVziVFppacVVyI/SxN+7SSDR4pbMTL8 bgwV1AiQSYiArYaNzVFowmA+XtJCRbGwliX7dHrpsjPLbMOYm99mtlIXnmwPEFGZvG0R ONOH+q1U3Ldrl8abF6Mt8qiNuRACywOyjSbj/JsrYv1ig+QHuFjeDYTtzHkQaMREF4vt tTusia2J5PjLvmQSXF6Af8w89gcJqht5AJhyPYkoNVgyl3wU3pf9lhnX5SgKzzo1aIEm 8I1xxVK871mS5f4DDjiiaepju+zIriym7XQGJIcoV7L0zcT/Oe33avHMg5s4gHTiaESf wo8g== X-Gm-Message-State: AO0yUKVVn7/yEvUr43k3ulfTzsloTDPfZ8qEN7AwfUmc6nFYNLLTS7xk /yos9ywyrUlpkaSybi5OLnt4WA== X-Google-Smtp-Source: AK7set81vQtZKuJ/VbVIcptx+2dxX/SQ85hdp3fzFRGeG9ds7AjBU/zKwR4t1eB350MeJFtKE/Pglg== X-Received: by 2002:a17:902:ab02:b0:196:8d96:dc6b with SMTP id ik2-20020a170902ab0200b001968d96dc6bmr1930869plb.2.1676454123202; Wed, 15 Feb 2023 01:42:03 -0800 (PST) Received: from [10.200.11.190] ([139.177.225.228]) by smtp.gmail.com with ESMTPSA id jh9-20020a170903328900b0018b025d9a40sm7944042plb.256.2023.02.15.01.41.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Feb 2023 01:42:02 -0800 (PST) Message-ID: Date: Wed, 15 Feb 2023 17:41:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH] mm: page_alloc: don't allocate page from memoryless nodes Content-Language: en-US To: Mike Rapoport , Michal Hocko Cc: David Hildenbrand , Vlastimil Babka , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Teng Hu , Matthew Wilcox , Mel Gorman , Oscar Salvador , Muchun Song , x86@kernel.org References: <67240e55-af49-f20a-2b4b-b7d574cd910d@gmail.com> <22f0e262-982e-ea80-e52a-a3c924b31d58@redhat.com> <4386151c-0328-d207-9a71-933ef61817f9@redhat.com> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E292540002 X-Stat-Signature: 64qfb9w6pwp38o6pbtu39kxyhbktozcj X-Rspam-User: X-HE-Tag: 1676454124-82407 X-HE-Meta: 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 XkWy1qBl 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 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 2023/2/15 17:30, Mike Rapoport wrote: > On Tue, Feb 14, 2023 at 02:38:44PM +0100, Michal Hocko wrote: >> On Tue 14-02-23 12:58:39, David Hildenbrand wrote: >>> On 14.02.23 12:48, David Hildenbrand wrote: >>>> On 14.02.23 12:44, Mike Rapoport wrote: >>>>> (added x86 folks) >>>>> >>>>> On Tue, Feb 14, 2023 at 12:29:42PM +0100, David Hildenbrand wrote: >>>>>> On 14.02.23 12:26, Qi Zheng wrote: >>>>>>> On 2023/2/14 19:22, David Hildenbrand wrote: >>>>>>>> >>>>>>>> TBH, this is the first time I hear of NODE_MIN_SIZE and it seems to be a >>>>>>>> pretty x86 specific thing. >>>>>>>> >>>>>>>> Are we sure we want to get NODE_MIN_SIZE involved? >>>>>>> >>>>>>> Maybe add an arch_xxx() to handle it? >>>>>> >>>>>> I still haven't figured out what we want to achieve with NODE_MIN_SIZE at >>>>>> all. It smells like an arch-specific hack looking at >>>>>> >>>>>> "Don't confuse VM with a node that doesn't have the minimum amount of >>>>>> memory" >>>>>> >>>>>> Why shouldn't mm-core deal with that? >>>>> >>>>> Well, a node with <4M RAM is not very useful and bears all the overhead of >>>>> an extra live node. >>>> >>>> And totally not with 4.1M, haha. >>>> >>>> I really like the "Might fix boot" in the commit description. >>>> >>>>> >>>>> But, hey, why won't we just drop that '< NODE_MIN_SIZE' and let people with >>>>> weird HW configurations just live with this? >>>> >>>> >>>> ;) >>>> >>> >>> Actually, remembering 09f49dca570a ("mm: handle uninitialized numa nodes >>> gracefully"), this might be the right thing to do. That commit assumes that >>> all offline nodes would get the pgdat allocated in free_area_init(). So that >>> we end up with an allocated pgdat for all possible nodes. The reasoning IIRC >>> was that we don't care about wasting memory in weird VM setups. >> >> Yes, that is the case indeed. I suspect the NODE_MIN_SIZE is a relict of >> the past when some PXM entries were incorrect or fishy. I would just >> drop the check and see whether something breaks. Or make those involved >> back then remember whether this is addressing something that is relevant >> these days. Even 5MB node makes (as the memmap is allocated for the >> whole memory section anyway and that is 128MB) a very little sense if you ask me. > > How about we try this: I'm curious how we can test this? I guess no one remembers the historical background of NODE_MIN_SIZE. :( > > From b670120bcacd3fe34a40d7179c70ca2ab69279e0 Mon Sep 17 00:00:00 2001 > From: "Mike Rapoport (IBM)" > Date: Wed, 15 Feb 2023 11:12:18 +0200 > Subject: [PATCH] x86/mm: drop 4MB restriction on minimal NUMA node size > > Qi Zheng reports crashes in a production environment and provides a > simplified example as a reproducer: > > For example, if we use qemu to start a two NUMA node kernel, > one of the nodes has 2M memory (less than NODE_MIN_SIZE), > and the other node has 2G, then we will encounter the > following panic: > > [ 0.149844] BUG: kernel NULL pointer dereference, address: 0000000000000000 > [ 0.150783] #PF: supervisor write access in kernel mode > [ 0.151488] #PF: error_code(0x0002) - not-present page > <...> > [ 0.156056] RIP: 0010:_raw_spin_lock_irqsave+0x22/0x40 > <...> > [ 0.169781] Call Trace: > [ 0.170159] > [ 0.170448] deactivate_slab+0x187/0x3c0 > [ 0.171031] ? bootstrap+0x1b/0x10e > [ 0.171559] ? preempt_count_sub+0x9/0xa0 > [ 0.172145] ? kmem_cache_alloc+0x12c/0x440 > [ 0.172735] ? bootstrap+0x1b/0x10e > [ 0.173236] bootstrap+0x6b/0x10e > [ 0.173720] kmem_cache_init+0x10a/0x188 > [ 0.174240] start_kernel+0x415/0x6ac > [ 0.174738] secondary_startup_64_no_verify+0xe0/0xeb > [ 0.175417] > [ 0.175713] Modules linked in: > [ 0.176117] CR2: 0000000000000000 > > The crashes happen because of inconsistency between nodemask that has > nodes with less than 4MB as memoryless and the actual memory fed into > core mm. > > The commit 9391a3f9c7f1 ("[PATCH] x86_64: Clear more state when ignoring > empty node in SRAT parsing") that introduced minimal size of a NUMA node > does not explain why a node size cannot be less than 4MB and what boot > failures this restriction might fix. > > Since then a lot has changed and core mm won't confuse badly about small > node sizes. > > Drop the limitation for the minimal node size. > > Link: https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/ > Signed-off-by: Mike Rapoport (IBM) > --- > arch/x86/include/asm/numa.h | 7 ------- > arch/x86/mm/numa.c | 7 ------- > 2 files changed, 14 deletions(-) > > diff --git a/arch/x86/include/asm/numa.h b/arch/x86/include/asm/numa.h > index e3bae2b60a0d..ef2844d69173 100644 > --- a/arch/x86/include/asm/numa.h > +++ b/arch/x86/include/asm/numa.h > @@ -12,13 +12,6 @@ > > #define NR_NODE_MEMBLKS (MAX_NUMNODES*2) > > -/* > - * Too small node sizes may confuse the VM badly. Usually they > - * result from BIOS bugs. So dont recognize nodes as standalone > - * NUMA entities that have less than this amount of RAM listed: > - */ > -#define NODE_MIN_SIZE (4*1024*1024) > - > extern int numa_off; > > /* > diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c > index 2aadb2019b4f..55e3d895f15c 100644 > --- a/arch/x86/mm/numa.c > +++ b/arch/x86/mm/numa.c > @@ -601,13 +601,6 @@ static int __init numa_register_memblks(struct numa_meminfo *mi) > if (start >= end) > continue; > > - /* > - * Don't confuse VM with a node that doesn't have the > - * minimum amount of memory: > - */ > - if (end && (end - start) < NODE_MIN_SIZE) > - continue; > - > alloc_node_data(nid); > } > -- Thanks, Qi