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 DF66AC636CC for ; Wed, 15 Feb 2023 10:08:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 58C4A6B007D; Wed, 15 Feb 2023 05:08:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 53BD26B0080; Wed, 15 Feb 2023 05:08:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3C1446B0081; Wed, 15 Feb 2023 05:08:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 274BD6B007D for ; Wed, 15 Feb 2023 05:08:46 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id D119D814DA for ; Wed, 15 Feb 2023 10:08:45 +0000 (UTC) X-FDA: 80469102210.12.F10B230 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf23.hostedemail.com (Postfix) with ESMTP id 0DC09140003 for ; Wed, 15 Feb 2023 10:08:43 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=aaeJnWow; spf=pass (imf23.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676455724; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=pEm41LNU7RJQhSFEkoNbn3IvUUrT5ao5ZPxYnO5ese4=; b=f0GMnBZXJEXAWJmwCkyQAKLhrqgl+FDl0TPub3oPFWL/bUTU0+kr73b4BG62UfBckBmFlM AScBbz1ZZ1IKWmC93O3Xn/inkIdlmyALoZF3W5G4iolIunT5Xr6HHOyikEBGbIX6lDJmQq 66eltH6NwGYk/zufkH22HRPT98kHGow= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=aaeJnWow; spf=pass (imf23.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676455724; a=rsa-sha256; cv=none; b=AbQ5ke4Z8mMyJqrv6O2IQ+SrtvYvq3EybPg1pRc/g0M+uxOS56gA4uHQeH2p3+5qVfftED pWOB8Tx10q5EHUy4P97/20OaNrpKoRHG6/udQITT3mVoDU5OJzkvESgX78Wp2ptaUzj5bX 2YvyYxe/R+6817e6ddAeE4mhrCv4Cc4= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3F83E61AEC; Wed, 15 Feb 2023 10:08:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66E31C433D2; Wed, 15 Feb 2023 10:08:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676455722; bh=+ErR1mhwcLA7orp3FBuWvTJemO2srg6qY9UPnHKqXGU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aaeJnWow7IaVfAqAjP1aeJwDUxiiZsV1ZF1vT4/WQ06fxSvJsuNHYvB2u6iTbRf2a PxjrEEjMuHXBNYvcFGrEAGg7YViLPG4jd3CQ61cjAgT+IWpJ/vOkuzu3yluuKz9dyd lblUsWv/Z5Ran8LmUJu/NDSdi9gdQK+7XtXrLHiMz0V5QUKd8kuTrvd3RMKQr6xCXG lEAgn/2GtO+f2MFYqL6PNHyWjM2PicmZzUDjoFu9Oi/4Xtuqpfgj7ytOLTO6mTo7kd SLTUCXhKBKPlUVi33GRTkkEPwrDX6WDM/aWMJkskLQAWIQ8Pm65StJclhzFLnYqMMj t5m6wK3bPGfkA== Date: Wed, 15 Feb 2023 12:08:27 +0200 From: Mike Rapoport To: Qi Zheng Cc: Michal Hocko , 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 Subject: Re: [PATCH] mm: page_alloc: don't allocate page from memoryless nodes Message-ID: References: <67240e55-af49-f20a-2b4b-b7d574cd910d@gmail.com> <22f0e262-982e-ea80-e52a-a3c924b31d58@redhat.com> <4386151c-0328-d207-9a71-933ef61817f9@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0DC09140003 X-Stat-Signature: ksds761sr6pufsqfyjgsgqi39556dyat X-Rspam-User: X-HE-Tag: 1676455723-623573 X-HE-Meta: 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 UmvCmaWs 9watxNAORq2znL/DYSjS4M911sq5n60xnNRu+7Lb+ZuI4Nc4TepnKTgEULM3LQFRQ/9GW/8PigLalEQyL8sxmkEfUqmrY0mZVun0rIER0FpSeK0AEkkCDHdCALI4MqDaubanubmN19ttjCBjIdnhrCV/Z/wBcZGDTqos/a93umoHh32QRzFHhmHsiFYMGTVLFiQgQWnKJxXOeXeQi6Utz69aRUi+3/isPMpXnqf5147dBwYFarZZKCSoP/sRPnj6zxBWBzthh1vbRkWw0tbaX/YF/OxPZS+tVTI8eARp+qIRbSKUw1CU1RmQf0CBRAzcJBDMlooTjS6DCkWvhBp7QbxSGuIRYxv8W5p/601HMxrUaMtOd8p4gSf9baDUfxVLv4XVii7zwU0Yi9Dhw6cfvOiEM6/twL1JtqliVfXR12w3Be4H+zs7fNPPd4Tx1Z/iV3Bwoc/HUWOINQKgyPm3oD0S5y5lotjiu01rC 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 Wed, Feb 15, 2023 at 05:41:52PM +0800, Qi Zheng wrote: > > > 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. :( At the very least we can verify that your setup works fine with this ;-) Of course we cannot test the exact same configuration that NODE_MIN_SIZE was supposed to fix, but there was a lot of effort to make core mm initialization robust to cope with weird memory layouts and I'm quite confident this won't break anything. > > 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 -- Sincerely yours, Mike.