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 2D482C021B8 for ; Tue, 4 Mar 2025 10:21:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B4AC1280002; Tue, 4 Mar 2025 05:21:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AD388280001; Tue, 4 Mar 2025 05:21:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 94D15280002; Tue, 4 Mar 2025 05:21:46 -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 74F8D280001 for ; Tue, 4 Mar 2025 05:21:46 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 184241CBF66 for ; Tue, 4 Mar 2025 10:21:46 +0000 (UTC) X-FDA: 83183477412.26.192186F Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf23.hostedemail.com (Postfix) with ESMTP id 3949C140004 for ; Tue, 4 Mar 2025 10:21:43 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="GrKuga/H"; spf=pass (imf23.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 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=1741083703; 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=G0GXHJX1K7E5e2wBQk1oB0WcGldIFjvSOHPSzQdYz+4=; b=nE/X7l/gj89o9jJwW0Dx1TIqTwqeRKUWYO/935xre46K3nWj83EI0ArB5Cc3PNM3kw09QQ a+Rr1pFlr68sVasXJegkFta3a9jC+ovxmtBMsF6ZNgqDOAwrSiEVJnSoqxx48CkNK/XULR UuiOzQg7/6SPqSgXCToWYLt+jzE1Da0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741083703; a=rsa-sha256; cv=none; b=kiqAs7YqyC7P+V2+tT0EoE6dKqaKSp2JjIT7/5dHoraSbq1WH5Z6j+gSf2uuT4XXBqL8B8 clvAPgE1hfdW+PEgCPu0B5Cvu1VAGRtyDFa9cxJSLFd0TmVZosdCpsjijHIGOegdPGCjru liRPj+Qae3b5uMAItoz6qdAdf/O8fhs= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="GrKuga/H"; spf=pass (imf23.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741083702; 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=G0GXHJX1K7E5e2wBQk1oB0WcGldIFjvSOHPSzQdYz+4=; b=GrKuga/Hfj+FT7OXTfIsuSmlv5lNxn/b4wdhugcRBjlhiDVM90qFzWjqzpHJcuH/TMI1Du vzbzcMZGz9W/Hxf1l/QhmXFUdHKv2QCu+tSgwejnGTVGPK2ZMUShniiXSzNo0tkSR3kQIa AzM0SZhGKKeDzaYX34gSmh/rjkybmAQ= 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-206-21KUOGSFOTKH25nmwJDhEQ-1; Tue, 04 Mar 2025 05:21:41 -0500 X-MC-Unique: 21KUOGSFOTKH25nmwJDhEQ-1 X-Mimecast-MFC-AGG-ID: 21KUOGSFOTKH25nmwJDhEQ_1741083700 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3910876fce0so1374980f8f.2 for ; Tue, 04 Mar 2025 02:21:41 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741083700; x=1741688500; 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=G0GXHJX1K7E5e2wBQk1oB0WcGldIFjvSOHPSzQdYz+4=; b=HHrgXKZidFSl5GVagEsUSt6/ZgU5HqJheLzqjPb0d5T1HjMDvsX1DhTtXVNaqJzTCi lPWjOtRdCJld/RWZppYUX83382cfYeI78BMnA70RE9yq6+HV0tM9f/tnDnwp7rpJKwTy KVjAdb71GZoQPVseLBXuSPIcYWZB8z6FCgLNGXm+yoXjPfYKyKkWLPnAPQP0C+XDweZd m5memXvDsDLJ3cFjad4a2CDqzrKbRv0xm/PMuY0K33bESDkx2aPeiNtuotgjYP+9LskE Sr7/A67mrb36RZS09XKo9UNQbmXtSXLFH1xrmAVh0dDdQMEGS++Tckg7elcre1vVqKve 5D4A== X-Forwarded-Encrypted: i=1; AJvYcCXxPV7Pm/CLu6LnotwFPVriRnQHfju/+1fxtjAy0pauUOnl+yKx2y1JNdrGrgzYg3IaX6T/ySTF7A==@kvack.org X-Gm-Message-State: AOJu0YzwKB5Xeu2Rtg94Jrk4xGBAmuinGjjpJEV2M5VhASEDMCASD5YM ojGgixANkJFU4CJqdjtkBHGc3aMA5pwN+hLuSmBQcXgtGPlC7NxWuSgbKeFbl+ORpVpSTlP/8p5 z011UD6J8a4S9/6kR9iPt7ZM+emK0zEZp5elbv0dS2kX1iy3C X-Gm-Gg: ASbGnctX4WNHjqmc1E4G1CunaXqVXWfUwE9KIEhFsAwe+dgv6TDQPdVBo/Sy4i79UQ6 evoeF+RUum8p7xjWLq6UTdomyKkjaJS8iulNxV1s5e/1DH1EJmy2Vhmuqs2CzDFueTyRTbWjhhy xwZfkFmh2AVBhrLg1x+0cBaHZEqM/+/nLJEv61vKpMu/06IuiD9k8fHRJ234e6AV2S7pqrgFR6W Q7ux/1zno4q0bgH36ldqiTr1/5AyoOL6GUjuJpfFZtHGgTyOXPG2Swt3rxIyPKROXqCEe9DSkwQ j/N4IuuGNL/OuDLtmrpvMWaaD6VErkHejPzIzKpuxtR6FxzK9hEEP+dTESReJWxrrkOvFwcnOpv SZIj2ZRkpD8EFD4WL3WHttu9wzqSrWldkv0rwpA2VYak= X-Received: by 2002:a5d:6c6e:0:b0:38d:c364:d516 with SMTP id ffacd0b85a97d-390eca81d4emr15654528f8f.54.1741083700179; Tue, 04 Mar 2025 02:21:40 -0800 (PST) X-Google-Smtp-Source: AGHT+IFoe+t9reG+q1KXFWE83QujE4ro+8v9oe5SMfx3hNgMcGBMtEEMSM8d0V6pJPgREtHTPyF6dQ== X-Received: by 2002:a5d:6c6e:0:b0:38d:c364:d516 with SMTP id ffacd0b85a97d-390eca81d4emr15654508f8f.54.1741083699822; Tue, 04 Mar 2025 02:21:39 -0800 (PST) Received: from ?IPV6:2003:cb:c736:1000:9e30:2a8a:cd3d:419c? (p200300cbc73610009e302a8acd3d419c.dip0.t-ipconnect.de. [2003:cb:c736:1000:9e30:2a8a:cd3d:419c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-390e4796517sm16996820f8f.5.2025.03.04.02.21.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Mar 2025 02:21:39 -0800 (PST) Message-ID: <54433b22-edaa-421e-9c99-6ee99734ab6d@redhat.com> Date: Tue, 4 Mar 2025 11:21:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 00/20] mm: MM owner tracking for large folios (!hugetlb) + CONFIG_NO_PAGE_MAPCOUNT To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, "Matthew Wilcox (Oracle)" , Tejun Heo , Zefan Li , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Jonathan Corbet , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Muchun Song , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn References: <20250303163014.1128035-1-david@redhat.com> <20250303144332.4cb51677966b515ee0c89a44@linux-foundation.org> 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: <20250303144332.4cb51677966b515ee0c89a44@linux-foundation.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: KV_zEyl32bfQNDRwlKARuvilln4Nk7fG_7vZ59mI1EU_1741083700 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-Stat-Signature: tkxqp17f1ofiu4kuuynbjgbmtjno4s81 X-Rspamd-Queue-Id: 3949C140004 X-Rspam-User: X-HE-Tag: 1741083703-759279 X-HE-Meta: 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 mVTvAeLv 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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 03.03.25 23:43, Andrew Morton wrote: > On Mon, 3 Mar 2025 17:29:53 +0100 David Hildenbrand wrote: > >> Some smaller change based on Zi Yan's feedback (thanks!). >> >> >> Let's add an "easy" way to decide -- without false positives, without >> page-mapcounts and without page table/rmap scanning -- whether a large >> folio is "certainly mapped exclusively" into a single MM, or whether it >> "maybe mapped shared" into multiple MMs. >> >> Use that information to implement Copy-on-Write reuse, to convert >> folio_likely_mapped_shared() to folio_maybe_mapped_share(), and to >> introduce a kernel config option that let's us not use+maintain >> per-page mapcounts in large folios anymore. >> >> ... >> >> The goal is to make CONFIG_NO_PAGE_MAPCOUNT the default at some point, >> to then slowly make it the only option, as we learn about real-life >> impacts and possible ways to mitigate them. > > I expect that we'll get very little runtime testing this way, and we > won't hear about that testing unless there's a failure. > > Part of me wants to make it default on right now, but that's perhaps a > bit mean to linux-next testers. Yes, letting this sit at least for some time before we enable it in linux-next as default might make sense. > > Or perhaps default-off for now and switch to default-y for 6.15-rcX? Maybe default-off for now, until we rebase mm-unstable to 6.15-rcX. Then, default on first in linux-next, and then upstream (6.16). > > I suggest this just to push things along more aggressively - we may > choose to return to default-off after a few weeks of -rcX. Yeah, I'm usually very careful; sometimes a bit too careful :) -- Cheers, David / dhildenb