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 BBC7EC3600C for ; Thu, 3 Apr 2025 13:08:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8F063280004; Thu, 3 Apr 2025 09:08:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 87661280001; Thu, 3 Apr 2025 09:08:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6CC2D280004; Thu, 3 Apr 2025 09:08:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 49B4C280001 for ; Thu, 3 Apr 2025 09:08:28 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id BD03C1A0778 for ; Thu, 3 Apr 2025 13:08:28 +0000 (UTC) X-FDA: 83292761496.09.4237F77 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf16.hostedemail.com (Postfix) with ESMTP id 1020D18000F for ; Thu, 3 Apr 2025 13:08:25 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=K5WamhON; spf=pass (imf16.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1743685706; 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=UG0JXGQ92TX1JQprqBBj5ySDoKcd5Kcj8ZtJqWU49eY=; b=TAlFqAIO8JZyCEhof9aiQ91zmAQrkLJVWfSdg+jauqFzixzhBYvjzkFByTh1err0ZE+Buz MajD4vZM5eMNjVmD3UIy2K+7/LcFq0Ae2qdrMX7sobeosN5K/YAFEEgpT3+bTDWmpkPd75 7Z1DP3UJxSfTrhuuDfu+WngtCngV+qw= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=K5WamhON; spf=pass (imf16.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1743685706; a=rsa-sha256; cv=none; b=pDnxL2N6Cboz95Kvd0KgYCCcnLWbsL6LO++pCYMpoVAMIr+rUc3rU/XkMj+ehzRqn1t8pH MCVeGyTRskH+NToqo+e9K4doK3Jox8NENs3JLz9WKn201K822wQxbRDn99ifZQHfv5h7GC VLHuWU0l0PGDPWZ90J9KsMVZ/SWheY0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743685705; 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:autocrypt:autocrypt; bh=UG0JXGQ92TX1JQprqBBj5ySDoKcd5Kcj8ZtJqWU49eY=; b=K5WamhON1RssWu9I9J+WRSGrHLSmUlzIB6e0k/IbrlQ3OKMRPIcLFe54fgZayhmFofcFef RIJwDNK2xisHtvvs4QHwMD3V4bieL+QJ7EZhzdC6vh0dw7Xg5OdSB300vZS84aCOinW/+B +R+kskbt1nENxUx4LxWvXbUlTvgQIIs= 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_256_GCM_SHA384) id us-mta-67-_jmvu_6uPIS-S16e3w_s0w-1; Thu, 03 Apr 2025 09:08:22 -0400 X-MC-Unique: _jmvu_6uPIS-S16e3w_s0w-1 X-Mimecast-MFC-AGG-ID: _jmvu_6uPIS-S16e3w_s0w_1743685701 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-43d007b2c79so6794045e9.2 for ; Thu, 03 Apr 2025 06:08:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743685701; x=1744290501; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:references:cc:to:from:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=UG0JXGQ92TX1JQprqBBj5ySDoKcd5Kcj8ZtJqWU49eY=; b=LmQhuKAo4gLawke6eZrfnP/LTj+IfIhWx2ARouiZGzF8CvTuP3DXavIyQpizotcbz0 9BWhFe6xKhyDbcqdxBfyy7TM3M2b5vJ98eU/oxL9pGHTH3EWYDSy9lEKcCS+yGr5jA/Z 8apnD4cxbMytc7OPlmLqXQD+F7NHbKxOk4Z8qgSdegljsGd9zBJMvHpJDyvCyCVraRxr R6Nfcqkd6d1dUN2nwemZrmPaRNrqp2whAjFf/iTcnSEdnRYbfT7+BOav1vVMPHeJVWsw IDWlZXYNp9BDT3P2dAut0x5asP445TMS1/H54USRfFqdcSi8nVADr0FzAjXdCwjBebZE BA/w== X-Forwarded-Encrypted: i=1; AJvYcCVcuzx/RGkRSKuGYCdHpRYEvFKhk3ZmbOT8gM09Mb0sY71PVLOZCy9KEEFV8v4l0Vpl79OXlHpc/Q==@kvack.org X-Gm-Message-State: AOJu0YyVf3l1ZAFSBOMBtTPEjrimJchNB5HMvb718urzwOUMi1VZusIB vNs10hoxv8NT0LfX4GZWFaYM7wncs6WJTvxm3ikDUKFzls+xAqZ6EfK/AE/HE3YUcw9h28XEwNn A2DwQtqC3d+pbOC2+vgXV6DTus5de50ryRaQj98u7uudG+jJ1 X-Gm-Gg: ASbGnctQNMzBm52Z4RbAe7Bzp3XOosLX8UYbtEvEgifElqAFOqCaTMjwgqbY55zFzo0 MnacBve4lDxOnefx+PIoFZa116aZ4iUpzSm/7fma1vMMuNZEzT6Hg0diIoo437qT2Fgu9igXac/ /VUfrK4vr9UK8cFQtwQ0KsXzJ3DsX/wfDFlymL/gtRsXp/uhEM8/J3N6RQLgqRzJ4jDOH9dv2EY gqknCzk998Akcb+OFPxsYUqOE98LH9BXsVyGhRBF5ZJe8keUmQjAFIMsrk1+uawxmgCGb1/czHQ 7U04flP7jcWadFg3huIlZ2uqh71LUx0y4GRBMgB4k4Yb/Uc3zvQa3896VgMkmK0qGxip/esmF5D RZZ83UAvCC82CSTfM47bgEU09YNPhU4uYCGdjmU/+dHA= X-Received: by 2002:a05:600c:1e1b:b0:43d:49eb:9675 with SMTP id 5b1f17b1804b1-43eb5c9588cmr63696605e9.22.1743685700998; Thu, 03 Apr 2025 06:08:20 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFmcyS+7VTW4hwaesOURF5FanebnuaYSox+R/Kxs8MWcv7LhisUBrutJ3czo6sDaeQ9Algdbw== X-Received: by 2002:a05:600c:1e1b:b0:43d:49eb:9675 with SMTP id 5b1f17b1804b1-43eb5c9588cmr63696215e9.22.1743685700602; Thu, 03 Apr 2025 06:08:20 -0700 (PDT) Received: from ?IPV6:2003:cb:c70a:7b00:54a7:eb96:63bc:ccf4? (p200300cbc70a7b0054a7eb9663bcccf4.dip0.t-ipconnect.de. [2003:cb:c70a:7b00:54a7:eb96:63bc:ccf4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43ec1794e94sm21726085e9.31.2025.04.03.06.08.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Apr 2025 06:08:19 -0700 (PDT) Message-ID: Date: Thu, 3 Apr 2025 15:08:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] Implement numa node notifier From: David Hildenbrand To: Oscar Salvador , Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hyeonggon Yoo <42.hyeyoo@gmail.com>, mkoutny@suse.com, Dan Williams , Jonathan Cameron References: <20250401092716.537512-1-osalvador@suse.de> <78c976ba-1eaf-47b7-a310-b8a99a3882e2@suse.cz> Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: GfFLhfQo__tXdniymNQpsoK9PLvcaNHDi78WWvqcjzY_1743685701 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1020D18000F X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 3k6rz8dwwk35sfsss4i73jb9f6m9qz88 X-HE-Tag: 1743685705-684860 X-HE-Meta: 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 f65KoCsS 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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: List-Subscribe: List-Unsubscribe: On 03.04.25 15:02, David Hildenbrand wrote: > On 02.04.25 19:03, Oscar Salvador wrote: >> On Wed, Apr 02, 2025 at 06:06:51PM +0200, Vlastimil Babka wrote: >>> What if we had two chains: >>> >>> register_node_notifier() >>> register_node_normal_notifier() >>> >>> I think they could have shared the state #defines and struct node_notify >>> would have just one nid and be always >= 0. >>> >>> Or would it add too much extra boilerplate and only slab cares? >> >> We could indeed go on that direction to try to decouple >> status_change_nid from status_change_nid_normal. >> >> Although as you said, slub is the only user of status_change_nid_normal >> for the time beign, so I am not sure of adding a second chain for only >> one user. >> >> Might look cleaner though, and the advantatge is that slub would not get >> notified for nodes adquiring only ZONE_MOVABLE. >> >> Let us see what David thinks about it. > > I'd hope we'd be able to get rid of the _normal stuff completely, it's seems > way to specialized. > > We added that in > > commit b9d5ab2562eceeada5e4837a621b6260574dd11d > Author: Lai Jiangshan > Date: Tue Dec 11 16:01:05 2012 -0800 > > slub, hotplug: ignore unrelated node's hot-adding and hot-removing > > SLUB only focuses on the nodes which have normal memory and it ignores the > other node's hot-adding and hot-removing. > > Aka: if some memory of a node which has no onlined memory is online, but > this new memory onlined is not normal memory (for example, highmem), we > should not allocate kmem_cache_node for SLUB. > > And if the last normal memory is offlined, but the node still has memory, > we should remove kmem_cache_node for that node. (The current code delays > it when all of the memory is offlined) > > So we only do something when marg->status_change_nid_normal > 0. > marg->status_change_nid is not suitable here. > > The same problem doesn't exist in SLAB, because SLAB allocates kmem_list3 > for every node even the node don't have normal memory, SLAB tolerates > kmem_list3 on alien nodes. SLUB only focuses on the nodes which have > normal memory, it don't tolerate alien kmem_cache_node. The patch makes > SLUB become self-compatible and avoids WARNs and BUGs in rare conditions. > > > How "bad" would it be if we do the slab_mem_going_online_callback() etc even > for completely-movable nodes? I assume one kmem_cache_alloc() per slab_caches. > > slab_mem_going_offline_callback() only does shrinking, #dontcare > > Looking at slab_mem_offline_callback(), we never even free the caches either > way when offlining. So the implication would be that we would have movable-only nodes > set in slab_nodes. > > > We don't expect many such nodes, so ... do we care? BTW, isn't description of slab_nodes wrong? "Tracks for which NUMA nodes we have kmem_cache_nodes allocated." -- but as there is no freeing done in slab_mem_offline_callback(), isn't it always kept allocated? (probably I am missing something) -- Cheers, David / dhildenb