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 5F527C54E4A for ; Fri, 8 Mar 2024 13:24:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 744A16B029F; Fri, 8 Mar 2024 08:24:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6CDD06B02A2; Fri, 8 Mar 2024 08:24:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 51FE96B02A5; Fri, 8 Mar 2024 08:24:24 -0500 (EST) 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 3BE746B029F for ; Fri, 8 Mar 2024 08:24:24 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id D4B20A1A0A for ; Fri, 8 Mar 2024 13:24:23 +0000 (UTC) X-FDA: 81873940806.04.E67912A 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 124B0140010 for ; Fri, 8 Mar 2024 13:24:19 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=jH9RxcVc; 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=1709904260; 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=gFlkabwZqKFxCKxsKuJlWikQ6ttLHeYy2agQBJH0FF8=; b=ocN/rth9Z9EXkdgkPczqYl5KCz1nLBwrJeOsxkF8gxCPyeEwu2wGNgTf5Fnx8jBJ1wc4eL WgDpW9XxRnpia1MPTaCLSXE1FkKmE7nuhd3yb85MOgqv6dJvLy6cqQYEmWC0RCpuICcjOU KbuSzOorhaiHp3VX1UEcH/nhUKx1AbM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709904260; a=rsa-sha256; cv=none; b=KTpNzJGyy1fahHtCEjb4sg0ZszUuXXM8e723i6LsBLt+UcnIbNp7Oe4Bwm9yd3AWSEBazy h/qtG4NmSaOCrbCdDhv0bmMxAqvb8HUml5w9cx3V9Oy5FvLwC8AZoId+H1Jbovs3prNyRN 7f9MnWlTYM371l6soDQ4YlD9d4qjVbU= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=jH9RxcVc; 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=1709904258; 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=gFlkabwZqKFxCKxsKuJlWikQ6ttLHeYy2agQBJH0FF8=; b=jH9RxcVcS28H2J97TG/yiFYQs0V4QDEde/W9RXPiQPU5TEjVLrJlf57D5AGkpC0pLvJRrp b14oB0WjkI85dFW56SXwU+t33Oyx8NffXr3Quqqkz8nyCJF21D+PzSXByHux1tqV0YME1B W+Dfrq/pfrweaY2QZgi4WeuFAgAN9Dw= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-284-GbxBuM2tO0ugt_495DdrSw-1; Fri, 08 Mar 2024 08:24:17 -0500 X-MC-Unique: GbxBuM2tO0ugt_495DdrSw-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4131c96569dso527385e9.3 for ; Fri, 08 Mar 2024 05:24:17 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709904256; x=1710509056; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :references:cc:to:content-language:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=gFlkabwZqKFxCKxsKuJlWikQ6ttLHeYy2agQBJH0FF8=; b=FEScmhzJokVXK6gRyu5Uk2njhXwd5xz5ZolLjGUkdzOULhA0arVXhQF4HPePomTANj Tfz4M0Jsgm+FLXxKjqWk6dG44vKG/54AgFnOZnZE6UCFfIeKhAmSjKnAxZLUMs1XMb0Y IZtPTwOCF6W/xfLWgzW7HYSYxnsEWnZUm0237fT6HgA4T2gLqf0OWHIL7E7PdD2lsEWW F85KmZKwndDqjApa0t28sTFtfwjgop2x731S8tmHh3lGTotT1ysS1RO16np3iVnunDww SkHixpuPn/29tHj3pE6QEWGJPnAGHI4aXHo0KAPVpciARoQR0lbtwyOjrNPObZacjkSs mrnA== X-Forwarded-Encrypted: i=1; AJvYcCU7qg+POfqPZ6knEm+pSEH4apUuYiYCtQS+DS+RaPk5ZRld9ym2rKdgZtb0kWKrlFIsAmC7wfBOmdaENEwWjV+VEEY= X-Gm-Message-State: AOJu0YweS4aT6QZS/fm8BwaoyVNKIx+S0CH0FvLNZ04PAOjRfHei1vZW r9zEzGMRoM+UAD/S8w+gUBlr+dsDE3538aWnRZQhPswmUNVO6M00VoVjYOPWyVf9YenpGZkCqiG NpI94CZr0DGxf4ZeLx0D+hq4/6m462/7arU6B9ihvl6LlSzi+ X-Received: by 2002:a05:600c:4f4d:b0:412:eb6e:1fdb with SMTP id m13-20020a05600c4f4d00b00412eb6e1fdbmr7091016wmq.40.1709904256040; Fri, 08 Mar 2024 05:24:16 -0800 (PST) X-Google-Smtp-Source: AGHT+IFKZ3sAL1SwJpjgNiqgMjRG4kmNg/y4CIEFUTeCzbQjSVkLElTzG/Y1SHY+NJBiXyoHZw8B5Q== X-Received: by 2002:a05:600c:4f4d:b0:412:eb6e:1fdb with SMTP id m13-20020a05600c4f4d00b00412eb6e1fdbmr7090998wmq.40.1709904255604; Fri, 08 Mar 2024 05:24:15 -0800 (PST) Received: from ?IPV6:2003:cb:c707:3500:5cd0:78d9:ca49:21f3? (p200300cbc70735005cd078d9ca4921f3.dip0.t-ipconnect.de. [2003:cb:c707:3500:5cd0:78d9:ca49:21f3]) by smtp.gmail.com with ESMTPSA id m8-20020a05600c4f4800b00413177c3f1dsm2265842wmq.18.2024.03.08.05.24.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 08 Mar 2024 05:24:14 -0800 (PST) Message-ID: <8e994734-1d3a-4c51-9c0b-4e2ce945f198@redhat.com> Date: Fri, 8 Mar 2024 14:24:13 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: prohibit the last subpage from reusing the entire large folio To: Ryan Roberts , Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org Cc: minchan@kernel.org, fengwei.yin@intel.com, linux-kernel@vger.kernel.org, mhocko@suse.com, peterx@redhat.com, shy828301@gmail.com, songmuchun@bytedance.com, wangkefeng.wang@huawei.com, xiehuan09@gmail.com, zokeefe@google.com, chrisl@kernel.org, yuzhao@google.com, Barry Song , Lance Yang References: <20240308092721.144735-1-21cnbao@gmail.com> <519fd6a7-072e-43a2-a9a8-2467ee783524@redhat.com> 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: X-Mimecast-Spam-Score: 0 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: 124B0140010 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: cwj8yfmm7ufz3wapjb5isw83ox9d7tjn X-HE-Tag: 1709904259-608501 X-HE-Meta: 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 6e1FytMD 9yH2naDeCSL0KMmHXn4gSPWh10PAhR1pG49nITTdVrpU3fs9gYJlcziX3u1gfg0pPEt4FDVQWcZHlH8JAYGpf4V8P6md47jRuozvLcD4fmywl2hBhrGDxhP08kPH0QCQzZdwQdEbgDzqEwRMRv++SP2xdWCPAPerllMJ1iwdZ3pc0G3BY/cjjCK0xDkNy4ZSZ+FSc6hd/ASbuCMRyirqSq0qNv6JmTrzEbQmrscDBulb0pGCHfKAz3AgiVFoFF2/twFa29WCtZ0bjHww+X5kqOLRjm7XJiDRmHBeR3dAHyPxQ2A/3wiIhABSZOgx/zGozhHU5akRJ5Wfh911HjN8Bn7JGlvSnuxnYQ78jZYtBbbZIEgijZIKPrhKYz0X7ldIKyeJmUlMka897Z/iDmsfR11UhtlbbUqCDAbXf0jqIu9f582s= 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: >>> This patch migrates the last subpage to a small folio and immediately >>> returns the large folio to the system. It benefits both memory availability >>> and anti-fragmentation. >> >> It might be controversial optimization, and as Ryan said, there, are likely >> other cases where we'd want to migrate off-of a thp if possible earlier. > > Personally, I think there might also be cases where you want to copy/reuse the > entire large folio. If you're application is using 16K THPs perhaps it's a > bigger win to just treat it like a base page? I expect the cost/benefit will > change as the THP size increases? Yes, I think for small folios (i.e., 16KiB) it will be rather easy to make a decision. The larger the folio, the larger the page fault latency due to scanning, copying, modifying, which can easily turn undesirable. At least when it comes to page reuse, I have some simple backup plans for small folios if I won't be able to make progress with my other approach. For larger folios, it won't really work/be desirable, though. -- Cheers, David / dhildenb