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 5706BC83033 for ; Tue, 1 Jul 2025 08:34:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C80A46B0099; Tue, 1 Jul 2025 04:34:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C57CB6B009C; Tue, 1 Jul 2025 04:34:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B46B26B00AA; Tue, 1 Jul 2025 04:34:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id A20DF6B0099 for ; Tue, 1 Jul 2025 04:34:45 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 3F6D18033E for ; Tue, 1 Jul 2025 08:34:45 +0000 (UTC) X-FDA: 83615034930.19.6217087 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf29.hostedemail.com (Postfix) with ESMTP id C6628120009 for ; Tue, 1 Jul 2025 08:34:41 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="N4acZb/R"; spf=pass (imf29.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=1751358881; 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=XqmCuun4O9S0uzldpDEz2Hy5OKYqaKQE+fhycCpdDZQ=; b=jPsblJlQCii21E5EljG0mFnG8mdtqz6GPAE4rSui4I5g99c51PJw1vtAMVmtNHWb3afTOL uwQo9tuWA5tmoevrniNZbI4YkFsBpn2Ukjon4mF6wNACjfxt+TSEfkXKRZ897zG/exq+K7 wFGx5ZolLnuB0fPzkdzMugCGLkK22k4= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="N4acZb/R"; spf=pass (imf29.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=1751358881; a=rsa-sha256; cv=none; b=WkSrZBKTItJayUZdWUeLT+4grRJyXUWzLTeM7WwzatZYCatjyvRtv45NksEI1yVVH/Ewup VPGSTj4N2x4me+agS1TwMIe9iKyYMUt4qDpCnZwj76zKsLwjuL826oyxk8yW3kQVmop5yy 9nE+XWOJrjw4UiYfTbym9DCMXw7JMiw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1751358881; 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=XqmCuun4O9S0uzldpDEz2Hy5OKYqaKQE+fhycCpdDZQ=; b=N4acZb/RB13QrbPeTSkoQloxeaxmyX9ZvD4wNDkaI0spBl7kxRo0fg3UGsAW65ztQ8ctO3 O8WFZsw0PLPhxiblo0asMNvmMC8vaOARHcB3LgLFW8fFYeGYfraJFnzNiJaTUFtjRhgZYX 70dSzkUuZXIk3hT2poBLO3zEhX4cKb4= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-615-dGVeo09ZNbm4UGByjRDoRQ-1; Tue, 01 Jul 2025 04:34:39 -0400 X-MC-Unique: dGVeo09ZNbm4UGByjRDoRQ-1 X-Mimecast-MFC-AGG-ID: dGVeo09ZNbm4UGByjRDoRQ_1751358878 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3a4edf5bb4dso3533876f8f.0 for ; Tue, 01 Jul 2025 01:34:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751358877; x=1751963677; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from: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=XqmCuun4O9S0uzldpDEz2Hy5OKYqaKQE+fhycCpdDZQ=; b=iV9Kt102z2QIdEkXCqgIIHTdiOie1Y/0ZVF1lFxBgxaUosFqcZpoycYAYlqwMXp9CJ ZvW5KO5E7OzWv1yTwBs24syVoL3Gn94XiaRubvme6a7PP86EAyD+wjJxEJZiV6jPEcTo fCfsFVbPPcnxxTu5sqLuIqrLrDDTENSMo6VD9y62AZrVJyGWDUVFu9Xr/9C/z8SuvgA9 GYMByNeXXqcUwLpYLNoEVxAOFXUM8T3z/X9gf+APPOUTyuuxuJF3NjN3SoN7pzo0XS0M T8eVSNMlSamM78VMz7JuiQLSt8GcTt/2UR+7sY3baNYE2scVn4oTjHIPPqLZiE1/965k xpVA== X-Forwarded-Encrypted: i=1; AJvYcCVXcpurh+9eisZ+sVv4sEFcTDWA2IdgDvOKqjIwq4hNX6LPrYkDK0ZCFAy/MnvjS38RGH07uXd+3Q==@kvack.org X-Gm-Message-State: AOJu0YwoBYCJDEMP8CKH+s9tygg6ZyGH8qpUbzw2TsAtHTZa2CF8xSzi hE8SGumj8bv7sv00A5ewCle0oSGS5UZXtPjAdbb7BS3gFmygZkfqh/kb7ZjnMis1dhxqZrdbviG gzqcWIa/v5u0QpM4VtFv6TsMqfze6VVif4HGU4q7PCsqYeJuq8pIW X-Gm-Gg: ASbGncvUb/z9vugu3bxglTqSNVVgzpJB7T27zAHfYjUtrthha8/xZru1A/Vu5sWeuxs xfdosSVewEomMOIoUmV0YFiEhDaPU8Xn9y61lCyy7ExMH0b01vCPM59Tbb/e9wH527fApPLCN2m ILSIWqhVjxHTEFdCRqlEqGKgAo0kGfYFOzqQmhVwoyvfnb5AF2qSKtUEF6niJcaifnzIkNuGTHe bJfC6U/n3Wxu+FAmVqbfwDR9ubHHZSnVTk4RHj8K2r+ZGKRNajMWrZ7+aFcNdjerMaiGzJxWxCh jQcZXAMAa0p1kpFW5leoRogCimVOS+llHu1t6hgDdBtkiDWvbbD5j+v364XJHmrabAajrMJr2G0 jN/6//efKJHz/5Wpgq6fUYoDj3rE9jTAUvOHKaUajySYmkSiNTA== X-Received: by 2002:a5d:60c4:0:b0:3a4:d898:3e2d with SMTP id ffacd0b85a97d-3a90d69c269mr11346926f8f.24.1751358877366; Tue, 01 Jul 2025 01:34:37 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEF8cObrwLhR7FvJoCAh0zan/cCbAjnhUquLcc9ptC1Omlee0lmAh8jtPfZiWWwygYZe4cdqg== X-Received: by 2002:a5d:60c4:0:b0:3a4:d898:3e2d with SMTP id ffacd0b85a97d-3a90d69c269mr11346880f8f.24.1751358876846; Tue, 01 Jul 2025 01:34:36 -0700 (PDT) Received: from ?IPV6:2003:d8:2f18:7500:202e:b0f1:76d6:f9af? (p200300d82f187500202eb0f176d6f9af.dip0.t-ipconnect.de. [2003:d8:2f18:7500:202e:b0f1:76d6:f9af]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a892e5f943sm12511942f8f.101.2025.07.01.01.34.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Jul 2025 01:34:35 -0700 (PDT) Message-ID: <84e1eeeb-c78f-4735-a6d2-4bb15ea1fbce@redhat.com> Date: Tue, 1 Jul 2025 10:34:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 04/29] mm/page_alloc: let page freeing clear any set page type To: Lorenzo Stoakes Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux.dev, linux-fsdevel@vger.kernel.org, Andrew Morton , Jonathan Corbet , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Jerrin Shaji George , Arnd Bergmann , Greg Kroah-Hartman , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Alexander Viro , Christian Brauner , Jan Kara , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Minchan Kim , Sergey Senozhatsky , Brendan Jackman , Johannes Weiner , Jason Gunthorpe , John Hubbard , Peter Xu , Xu Xin , Chengming Zhou , Miaohe Lin , Naoya Horiguchi , Oscar Salvador , Rik van Riel , Harry Yoo , Qi Zheng , Shakeel Butt References: <20250630130011.330477-1-david@redhat.com> <20250630130011.330477-5-david@redhat.com> <8c5392d6-372c-4d5d-8446-6af48fba4548@lucifer.local> <06e260cf-9b63-4d7c-809c-a9f2cda58939@lucifer.local> From: David Hildenbrand 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: <06e260cf-9b63-4d7c-809c-a9f2cda58939@lucifer.local> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: z95TgVtwY3M95DrqWxQTcqlLDegpNH8khOdU2XMCGPo_1751358878 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C6628120009 X-Stat-Signature: 51eewyd3d7j6m31pd64gqrnybnb4h4ra X-Rspam-User: X-HE-Tag: 1751358881-378429 X-HE-Meta: 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 8l9oO4dU ETV4+NcjCyXj1zPF5hzAJVlUqEuYttTMxsu51KR/JClB6+ghXVsdERyMWjalCmY5q9NXxgtjjv4sEHfWp1qJN+E28LQ5Cc6seFouLHtIUGACrR6pO0d/TR8kA2MnQhuWi/gPZMLjY+WwlIlqo5CVlrCF7SIsf4J7QwjN6M+YMY+3x9O9S5bjLGM2xrybzmLNfHhMjX/1Ki9ElDf+1Cd1pWSlO0f01ENfHP7RGnjwEnC/JiLJa5U6KeVu+J9ixGGksChAdrlZrtcLlZOW3z95N0a0NPxBYePp+jAambCGdDpEt1L4C6F+w0Qw89ORgHoZKuDNJI7dfLrenJy0YpBXcgSciwzOD6qRp+sa96HqkX97gtQFcEz/5NnpSai4i3t/UY17eMZoaYfJBaZPl/xhEY0Qcb6VbKKzJklJhxkF+JIHTRbFmErg0fcX/L2FFrPhcLiM87819rhccjnalXysq9IGEBMH8Ou6jjjKCp2atBqr23tuS7d8+8PxoXpL7loAOtZIzRsK8CIU3Ke8gX5ZWpWPmuS92h9Kye5vkSgTGMgiySqaUQdGERkVrUZRZGd0dfjy9XkqlnU5+GoM= 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 01.07.25 10:27, Lorenzo Stoakes wrote: > On Tue, Jul 01, 2025 at 10:17:13AM +0200, David Hildenbrand wrote: >> On 30.06.25 17:27, Lorenzo Stoakes wrote: >>> On Mon, Jun 30, 2025 at 02:59:45PM +0200, David Hildenbrand wrote: >>>> Currently, any user of page types must clear that type before freeing >>>> a page back to the buddy, otherwise we'll run into mapcount related >>>> sanity checks (because the page type currently overlays the page >>>> mapcount). >>>> >>>> Let's allow for not clearing the page type by page type users by letting >>>> the buddy handle it instead. >>>> >>>> We'll focus on having a page type set on the first page of a larger >>>> allocation only. >>>> >>>> With this change, we can reliably identify typed folios even though >>>> they might be in the process of getting freed, which will come in handy >>>> in migration code (at least in the transition phase). >>>> >>>> In the future we might want to warn on some page types. Instead of >>>> having an "allow list", let's rather wait until we know about once that >>>> should go on such a "disallow list". >>> >>> Is the idea here to get this to show up on folio dumps or? >> >> As part of the netmem_desc series, there was a discussion about removing the >> mystical PP checks -- page_pool_page_is_pp() in page_alloc.c and replacing >> them by a proper page type check. >> >> In that case, we would probably want to warn in case we get such a netmem >> page unexpectedly freed. >> >> But, that page type does not exist yet in code, so the sanity check must be >> added once introduced. > > OK, and I realise that the UINT_MAX thing is a convention for how a reset > page_type looks anyway now. > >> >>> >>>> >>>> Reviewed-by: Zi Yan >>>> Acked-by: Harry Yoo >>>> Signed-off-by: David Hildenbrand >>>> --- >>>> mm/page_alloc.c | 3 +++ >>>> 1 file changed, 3 insertions(+) >>>> >>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>>> index 858bc17653af9..44e56d31cfeb1 100644 >>>> --- a/mm/page_alloc.c >>>> +++ b/mm/page_alloc.c >>>> @@ -1380,6 +1380,9 @@ __always_inline bool free_pages_prepare(struct page *page, >>>> mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); >>>> page->mapping = NULL; >>>> } >>>> + if (unlikely(page_has_type(page))) >>>> + page->page_type = UINT_MAX; >>> >>> Feels like this could do with a comment! >> >> /* Reset the page_type -> _mapcount to -1 */ > > Hm this feels like saying 'the reason we set it to -1 is to set it to -1' :P Bingo! Guess why I didn't add a comment in the first place :P > > I'd be fine with something simple like > > /* Set page_type to reset value */ "Reset the page_type (which overlays _mapcount)" ? > > But... Can't we just put a #define somewhere here to make life easy? Like: Given that Willy will change all that soon, I'm not in favor of doing that in this series. -- Cheers, David / dhildenb