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 9B5B1C636D4 for ; Wed, 15 Feb 2023 09:44:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0DC436B0072; Wed, 15 Feb 2023 04:44:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 08C666B0075; Wed, 15 Feb 2023 04:44:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E48896B0078; Wed, 15 Feb 2023 04:44:05 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D35566B0072 for ; Wed, 15 Feb 2023 04:44:05 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id A38171A13F9 for ; Wed, 15 Feb 2023 09:44:05 +0000 (UTC) X-FDA: 80469040050.08.81686AC Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf09.hostedemail.com (Postfix) with ESMTP id 77510140014 for ; Wed, 15 Feb 2023 09:44:03 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=UZEGLBsX; spf=pass (imf09.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676454243; 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=L3U1FEZ4RqMM5/a4DwiutQ56IQqaMtzE5cgyWiSkU74=; b=K/rfWpLF2TVsD2OGfhXwBZ/wXcxjZEgC4EW4hrl3fTW2y6nKrs3wF7zj1I5S4aF8S82uyU 9r2ivPJjH5uLBPGnnEsoHg55dMpucNiN6XhbdwtUW9PtjQsY+lLA2Grbzeh1c6Tx68kL/n gDLIgOLe6qxw+DBY7cV7QvlQAlGeyww= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=UZEGLBsX; spf=pass (imf09.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676454243; a=rsa-sha256; cv=none; b=Ed0RbTCkmglo9GvRGtF+31O0pn42E9E05PupPrx7abimEoAy/U0O+lKwdRDGAPWcOp5hv1 w5Lv+1H1qkMlHFNzKQ6p9LrjQurUALukr6TSH2hrUr8SUcZgSvuvL9/r/BNLOnC4iLxjBS 2/XG6GNEYD9HuDvHhQXhTLQgSSCxdNw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676454242; h=from:from: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; bh=L3U1FEZ4RqMM5/a4DwiutQ56IQqaMtzE5cgyWiSkU74=; b=UZEGLBsXDejjApXhBDNPqqMuo88TGglVpp5TdFNMSs0TufMwzcaPmOYRwT9rkLn6hmTSBs rlUWk59piG1R9YQN4u9FYsdpuapbcZPJCe7HaC+92Jc4sModaMpViIRwZbkAvcCWq6cNmR Tlar94Yc7Fk6XSDbzvh+vlkfC5eQTjo= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-127-Tyl8zHvBNyK6SNJBng3Siw-1; Wed, 15 Feb 2023 04:44:01 -0500 X-MC-Unique: Tyl8zHvBNyK6SNJBng3Siw-1 Received: by mail-wm1-f71.google.com with SMTP id o42-20020a05600c512a00b003dc5341afbaso849208wms.7 for ; Wed, 15 Feb 2023 01:44:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:organization:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=L3U1FEZ4RqMM5/a4DwiutQ56IQqaMtzE5cgyWiSkU74=; b=haPIZJzbh941Nr6hsDT+D2I0Br2DuT185kNe7djl4jMfsfbjqmdUl6cD1uokjSICLc 7CAb4b52UE9U6dQYpCpBwXxpZlaYhEqK7YDD5f+FJVz8xqCskTBkJwAIvCmDfLimtVNb vItqmG8VIDwiSCt93IFJ7IEhOMJloquuzeNvUmfncxxYJw9W3dd/m4jjZQJPrprRhsSB 1EWXhJfWKqtDv+O7EuAQozD0bPuZ/g62HLMsNe2Iz9IHafqwudRvKZ7aW7p4tZSn7hD5 q7ZqjnCtXGNkxeiI/X4AC8qyRsKNdGrHFtoiRpctcB6ctbvXvk9PYvY0MPsfFAqrGOgc d6tw== X-Gm-Message-State: AO0yUKWa8Q2o+9MbEzapf7A8LYudXjraVSklUpg9EFElz0v5kD4NdbRh K5+DpsVmrkz1REC5e768RsczS8NmvKX9HdgaNeFADHlmmNbyLHcZ/wuROLJMGD4fs87RvHV0mQ6 T5WJtArdg46w= X-Received: by 2002:a05:600c:91d:b0:3e2:668:3ed7 with SMTP id m29-20020a05600c091d00b003e206683ed7mr224515wmp.1.1676454240167; Wed, 15 Feb 2023 01:44:00 -0800 (PST) X-Google-Smtp-Source: AK7set9rhiWAFNKJ4UTGGW2zvYD0ibyuRrJXlIe6DimzrLjLdqt60/8pIH/IQ//lvvP1+x1WW1WmOQ== X-Received: by 2002:a05:600c:91d:b0:3e2:668:3ed7 with SMTP id m29-20020a05600c091d00b003e206683ed7mr224495wmp.1.1676454239853; Wed, 15 Feb 2023 01:43:59 -0800 (PST) Received: from ?IPV6:2003:cb:c707:1400:b7d:4122:28d:f4c3? (p200300cbc70714000b7d4122028df4c3.dip0.t-ipconnect.de. [2003:cb:c707:1400:b7d:4122:28d:f4c3]) by smtp.gmail.com with ESMTPSA id y5-20020a05600c364500b003dffe312925sm1467030wmq.15.2023.02.15.01.43.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Feb 2023 01:43:59 -0800 (PST) Message-ID: <3a85b2b9-95fa-4123-a7a3-2bd6f8b35c13@redhat.com> Date: Wed, 15 Feb 2023 10:43:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH] mm: page_alloc: don't allocate page from memoryless nodes To: Mike Rapoport , Michal Hocko Cc: Qi Zheng , Qi Zheng , 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: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: cfcz3tntp8c9j6cpqc3pfmgaayzj1h48 X-Rspamd-Queue-Id: 77510140014 X-HE-Tag: 1676454243-161302 X-HE-Meta: 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 AYx2gSbq 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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 15.02.23 10:30, 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: > > 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); > } > Hopefully it fixes the issue. Acked-by: David Hildenbrand The 4 MiB looks like the magical MAX_ORDER (and/or pageblock) thingy to me. I recall that there were issues in the past when memory exposed to the buddy would only be partially covering a pageblock. IIRC, memblock should already take care to not expose memory to the buddy that is not aligned to MAX_ORDER boundaries -- correct? -- Thanks, David / dhildenb