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 EA28EC71157 for ; Tue, 17 Jun 2025 08:46:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4F5686B0092; Tue, 17 Jun 2025 04:46:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4CCC86B0093; Tue, 17 Jun 2025 04:46:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3BBF36B0095; Tue, 17 Jun 2025 04:46:02 -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 2BECF6B0092 for ; Tue, 17 Jun 2025 04:46:02 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id EB55BBF773 for ; Tue, 17 Jun 2025 08:46:01 +0000 (UTC) X-FDA: 83564260122.25.E1F299F Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf24.hostedemail.com (Postfix) with ESMTP id 70A3018000A for ; Tue, 17 Jun 2025 08:45:59 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=aBWcnHUx; spf=pass (imf24.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 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=1750149959; 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=+G3ospLMA2XYWkGUmnXr3TzBKv9Sa5X1cCVCRNuoDN0=; b=xfM1lTQSgN4MntbVCXsbslbKyvJW6NkaZsuPAPGuA3s3IDSiwGWIIp3Kprk2hx+rdwCxnT 76HgRKUsmkeCcMBeeFJNC2kGenKiPD/QRPun0aOQ8Okrl7YURqi9Ly462FZiDfunfROv6R jLbjZQKm2Q4PRwMnv+LTsxj1GJuncEA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1750149959; a=rsa-sha256; cv=none; b=kClljJU6a7Ak4uvu0evO0hsGFVNFoFdpEoeKJxX5n401fw2MKFgxG6GNe6ywQDxV2mgK2k XPIbANvBE5xOp6orSuWEO58uvIqLoCwCMxpueGQXaB56gCEuRt1KGzw1Hu1EWunXt2+Mrn 1uir/rBw8SajUq+SnMkaaEOYp4r8IhU= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=aBWcnHUx; spf=pass (imf24.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750149958; 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=+G3ospLMA2XYWkGUmnXr3TzBKv9Sa5X1cCVCRNuoDN0=; b=aBWcnHUxjcmgn8i1p4GK7Okt1CSjFVS1ZnidvTYn4E6vosxBFtE/WnTNfKbgbuMNVzDzdq gJFi0uHa/BQ7nVS10nMJApz6Mqk9a6Sy8V9wEGH+XvhAKWmVbc28AqiG8fl2+7M04+yc9B CJ4zVPdQm4gCtrJwmmb3U34uBXW6x1U= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-100-Ox6NHGccPI6eJqH1O-4frw-1; Tue, 17 Jun 2025 04:45:57 -0400 X-MC-Unique: Ox6NHGccPI6eJqH1O-4frw-1 X-Mimecast-MFC-AGG-ID: Ox6NHGccPI6eJqH1O-4frw_1750149956 Received: by mail-wr1-f71.google.com with SMTP id ffacd0b85a97d-3a4eee2398bso2283723f8f.1 for ; Tue, 17 Jun 2025 01:45:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750149956; x=1750754756; 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=+G3ospLMA2XYWkGUmnXr3TzBKv9Sa5X1cCVCRNuoDN0=; b=uu9wGkQWrOXM2EVynqUJV1gmBM34VWzDjr47DBXYpfZtf6Cj2yOiflRVXIYsFPbsH/ gRclhH/J55cUF2cxdL2ly9x42xYahX6EjoWqUOJVIZ2U3G7bmGFhzbamzpp1oXdyOm4B 8bfCIfSyGSQTJPWdeVA4OGuC7hPgGb+HiPz00+iO83EWh3wQbwpch5wZerCVorSqjPjr jbO9Ay0KF+2/UvIOEbs1RoYXnUJEA2reYn3TbKGVMMrpAn2Lv6Bqa755rk1LSed/p2jf zgbuIpvv+P7QYKTE+Dw/t8dfJzXEGZi379WLV7THQjY/QMMQuM46uuIAcSqnoK0WFIFk foDA== X-Forwarded-Encrypted: i=1; AJvYcCXZ9Iiwd5wsOrl3TvQzQtlBUlYglJsbv7JIgQOwkNoHgBo6MHV6nyxs7wjzHCBC37lMsZ25uttuFw==@kvack.org X-Gm-Message-State: AOJu0YyED4+YEID5EqZOyI5Dae+qUGkbQ40iaw2oSQ94QT1DH8WHFULO PIaEJm47XJJjTmQuT58YTTbvzKe5inLZLDu0jRCtRgcyTnwKhTOMzaH/4hE0q/7ty93q5K1QkOk sBWlwFpmiNAih6AHSJQ+EQz6Dle+wCLaXNtBR9AgEjm6fP7TgjQDH X-Gm-Gg: ASbGncuIoT7epmSsq8WVpoH/8NTFwY/U0VWURdmnACM3sUqoPGeFoR44TLh2+oNEcSm NpPuWemE7YlzSYsdus6JD+/BIJYrFNJ5X7mKLJ9RLCqSElFmE1GUAIHdq+xBcd+ClN0NmfnmteX o1WRyKulG1jXgmArPQGVywYq3/ZLBvtlaSDXenfl0tvBoTL1Ny0uE1u4KXh39cNyLwF6wWwDGv+ cKnYLFvEAxrFCy37l71CDKR/EN8jPjeenTGll1U9MMUNOaI6pcvDftRdEj58a1amgBOB5X0FOMg olR/u7JuWSsFlPgzzuLfgDyK+FG3URAnig6jx6KaS2Gm3QQPOQ0Ef+tVFb/B4WQlSNmwvXNjk+y sKB2Lt/IldmwhgOkW3PdpobLZU52JxcfHBOf4t+KE2vKAChU= X-Received: by 2002:a05:6000:2913:b0:3a5:2949:6c31 with SMTP id ffacd0b85a97d-3a5723aed54mr10046993f8f.42.1750149956428; Tue, 17 Jun 2025 01:45:56 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH5px/HdTcWLj11j/Dsf89T5YM5LlH/EwwnLUOgFBU0kgmDhtM72pP3A1pVNhVi646yxjX1dw== X-Received: by 2002:a05:6000:2913:b0:3a5:2949:6c31 with SMTP id ffacd0b85a97d-3a5723aed54mr10046959f8f.42.1750149955980; Tue, 17 Jun 2025 01:45:55 -0700 (PDT) Received: from ?IPV6:2003:d8:2f31:700:3851:c66a:b6b9:3490? (p200300d82f3107003851c66ab6b93490.dip0.t-ipconnect.de. [2003:d8:2f31:700:3851:c66a:b6b9:3490]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4532e2324c6sm166046645e9.12.2025.06.17.01.45.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Jun 2025 01:45:55 -0700 (PDT) Message-ID: <68d8c7ad-aea0-4556-be63-9b67d70e4386@redhat.com> Date: Tue, 17 Jun 2025 10:45:53 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/11] mm/mremap: introduce more mergeable mremap via MREMAP_RELOCATE_ANON To: Pedro Falcato Cc: Lorenzo Stoakes , Andrew Morton , Vlastimil Babka , Jann Horn , "Liam R . Howlett" , Suren Baghdasaryan , Matthew Wilcox , Rik van Riel , Harry Yoo , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Jakub Matena , Wei Yang , Barry Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <7e51e1e2-7272-48d5-9457-40ab87ad7694@redhat.com> <76zi626uk53dtfzmezzt6cfz45ansam2gpcumddqxnipnw5jkh@qwfzoxgi255b> 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: <76zi626uk53dtfzmezzt6cfz45ansam2gpcumddqxnipnw5jkh@qwfzoxgi255b> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: abEAjCtXxRdeDgRbLM6Rqbbb_hUNgDiMMh_I1niUUL4_1750149956 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: rspam11 X-Rspamd-Queue-Id: 70A3018000A X-Stat-Signature: aw5p5uiy3xchij7rga36htw8qrtgtw8r X-HE-Tag: 1750149959-933160 X-HE-Meta: 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 p3xb9Z2B 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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 17.06.25 10:34, Pedro Falcato wrote: > On Mon, Jun 16, 2025 at 10:41:20PM +0200, David Hildenbrand wrote: >> On 16.06.25 22:24, David Hildenbrand wrote: >>> Hi Lorenzo, >>> >>> as discussed offline, there is a lot going on an this is rather ... a >>> lot of code+complexity for something that is more a corner cases. :) >>> >>> Corner-case as in: only select user space will benefit from this, which >>> is really a shame. >>> >>> After your presentation at LSF/MM, I thought about this further, and I >>> was wondering whether: >>> >>> (a) We cannot make this semi-automatic, avoiding flags. >>> >>> (b) We cannot simplify further by limiting it to the common+easy cases >>> first. >>> >>> I think you already to some degree did b) as part of this non-RFC, which >>> is great. >>> >>> >>> So before digging into the details, let's discuss the high level problem >>> briefly. >>> >>> I think there are three parts to it: >>> >>> (1) Detecting whether it is safe to adjust the folio->index (small >>> folios) >>> >>> (2) Performance implications of doing so >>> >>> (3) Detecting whether it is safe to adjust the folio->index (large PTE- >>> mapped folios) >>> >>> >>> Regarding (1), if we simply track whether a folio was ever used for >>> COW-sharing, it would be very easy: and not only for present folios, but >>> for any anon folios that are referenced by swap/migration entries. >>> Skimming over patch #1, I think you apply a similar logic, which is good. >>> >>> Regarding (2), it would apply when we mremap() anon VMAs and they happen >>> to reside next to other anon VMAs. Which workloads are we concerned >>> about harming by implementing this optimization? I recall that the most >>> common use case for mremap() is actually for file mappings, but I might > > realloc() for mmapped allocations commonly calls mremap(), FYI (at least for > glibc, and musl; can't bother to look at the rest). Good point. Only for larger areas, I assume, where glibc would already fallback to expensive mmap()+munmap() instead of using the optimized sparse area. > >>> be wrong. In any case, we could just have a different way to enable this >>> optimization than for each and every mremap() invocation in a process. > > /me thinks of prctl I didn't want to spell that out :P I don't think this would have to be configurable per process ... > > :P > > > FWIW, with regards to the whole feature: While I do understand it's purpose ( > relocating anon might be too much for most workloads, but great for some), I'm > uncomfortable with the amount of internals we're exposing here. Who's to say > this is how mm rmap looks in 20 years? And we're stuck maintaining the userspace > ABI until then. Yes. > > Personally, I would prefer if we just had a flag 'MREMAP_HARDER' that would > vaguely be documented as "mremap but harder, even if have to do a little more > work". Then we could move things around without promising RELOCATE_ANON makes > conceptual sense, and userspace wouldn't have to think through the implications > of such a flag by reading Lorenzo's great book. Even such a flag is just weird. Next time we do MREMAP_EVEN_HARDER mremap() is already an expensive operation ... so I think we need a pretty convincing case to make this configurable by the user at all for each individual mremap() invocation. -- Cheers, David / dhildenb