From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 37BF020D50C for ; Mon, 11 Aug 2025 09:49:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754905770; cv=none; b=L4t/fwO1SWaEXpV2F34BV6wS152dzVQ76ZtUqnnpmHHBVglDH3A7Ziy/wduWn1F/hs7Qa9hfvyVFEMgX2f0NjnHmr5B/srNEZZOAY+DOA6dzvyccBQTDqGuu13I8qDVXc+6+h1er5Ia8slfEHs+Y8UUhJjcd5nfe2rbsxY4efzA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754905770; c=relaxed/simple; bh=YSH8u5PGqlODmLctM5GhdiruLiZoyKvrWvgnlKQlSMc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=k5ng++RAw7FJNM4Dip9VgOK4vNwPSjzW7QwiB4E9w/6N1XaFbCErgz71Xbezg0X2glUoAilG7YHRghvwvu3sVQ84DS/nvM0JqKvlZ4wHdA9ACiV/2wbcyqYYJJe2U1E9a0NDaW5v35HzF9InnATSDg05bOrZgqSmTwHELtk8rxo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=VWYv7bV6; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VWYv7bV6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1754905766; 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=zy7zoeBHdfB1I6ns8dWDx/bnOQrMxjU4C6kURFFGtA8=; b=VWYv7bV6C/BQN5hkAjr/z90J1ZBFgx+Pui0b8UHAYtTbwHTxU+35QAWGn2mm4JEUhI/6vb BpdZYlq+YsbHSuUc9IigqvaFzg40/Dy5wLibKOc0HouaV/AbkRoE/qJes8EYUlgbAOKrEP YkUuAZLlBV7dKY5v9jf5CEvg9CC0sd8= 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-213-o5deNP7KP--dAreEdUDYtg-1; Mon, 11 Aug 2025 05:49:25 -0400 X-MC-Unique: o5deNP7KP--dAreEdUDYtg-1 X-Mimecast-MFC-AGG-ID: o5deNP7KP--dAreEdUDYtg_1754905763 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-459d4b5db81so23228825e9.2 for ; Mon, 11 Aug 2025 02:49:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754905763; x=1755510563; 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=zy7zoeBHdfB1I6ns8dWDx/bnOQrMxjU4C6kURFFGtA8=; b=RmTZ6WlXucCQ/63PSh7q5wZ0Umo1rWUnQQ2E80Hsu//oXoGsOKK0RZRr7ANAyn41m1 6xkbbjxrSaVQl+2jvEw71KiO2zA5GC9Borqy2+JDviq2ZymJT/i7tUxY70q7I4xMLpDn OWAGdXFg1VdIR8DApp1VYMbDufFxEItwTtd+F++5dNGBsOT356IwlgGg9BRgXP+V2UfT fnegEd7A7dUVJwOACDkP5mzhYKMdzpFG7/94wNKOAC0q7rgQe8ZWLSON8t6mrf1jThrg D/dNQjqpVofGRs1pEowcWTxDI2UwsRkouhv5drwaOX8OBwdCDx2aV7ojA3uZa2KP6IAA 5kFw== X-Forwarded-Encrypted: i=1; AJvYcCUwG6o/HwfKerfZ0RotyzPcvuBoYvQ267t8kHDjfxRqEOeUYhON0KSKS7y22rr5F+kFLDdOzNF6rXq8aCU=@vger.kernel.org X-Gm-Message-State: AOJu0YxxODYVMB28poX5YZDhVuSz5FzY9PSUzo7gTi4AYWx6pHniw9SI QeqMotGNyPnono7YYehn08k61pFcC+MbMYQ4ahUthYXUgogu3QMr4OOIS31wEfwcu126SVz8FoP 2ksN3LhXcCyP/CvHkh20EoNKmJN3rVBw+4Hfxj30efPsRtS1dgWZC5MbiDCwQ7K/J/g== X-Gm-Gg: ASbGncsU/ssa7In5Ow7MPmXkM5rHfhxOwiZYw2wV0prWXHWXyLtTrav9uEDbQkIXrcT VEtAktgSvTFwS519VVvfsn/OWBlPMO0hEzudSmDp89VA/opBKtUn/RvCPSnb2bdpwOFTAMuF5qq nPahXbrxvvFlRV+0gdyfmybn3D9K6zlPvgUam2rDX9obVmxrrajJvvuo0geifUYIQCfDQjJP89f jlVQHmXq7eLprmX58wgScLU5Nm39BNCpfxTMF0gYy1T7i1bnvn/kmUZCpp+s6efwPvETc5jES3G OM6lB4rkZ0BZGf+W8xLMOX+BeEf+RIsjmiVe2t4ctNqqqaWXN7FOv7RXj8nV3hZ8Lz2FCKgp7ST uR8QP3I1VseRqqV1w7ovK5ozamhF/sBb5Ela5BnoZPDf7l8D1ryeZRaCIHTRhu/iM/ho= X-Received: by 2002:a05:600c:8207:b0:459:dc81:b189 with SMTP id 5b1f17b1804b1-459f4fc40e3mr130800575e9.31.1754905762853; Mon, 11 Aug 2025 02:49:22 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGEa+lMPdCvEQQa/1iCFQjPws3MuVXvht3etKiuOL4kCcQ5Vr73iEgsX0YCT2GWYa35XBoE9g== X-Received: by 2002:a05:600c:8207:b0:459:dc81:b189 with SMTP id 5b1f17b1804b1-459f4fc40e3mr130800075e9.31.1754905762394; Mon, 11 Aug 2025 02:49:22 -0700 (PDT) Received: from ?IPV6:2003:d8:2f06:a600:a397:de1d:2f8b:b66f? (p200300d82f06a600a397de1d2f8bb66f.dip0.t-ipconnect.de. [2003:d8:2f06:a600:a397:de1d:2f8b:b66f]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b79c3b9386sm40066956f8f.18.2025.08.11.02.49.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Aug 2025 02:49:21 -0700 (PDT) Message-ID: Date: Mon, 11 Aug 2025 11:49:19 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/5] add persistent huge zero folio support To: Kiryl Shutsemau , "Pankaj Raghav (Samsung)" Cc: Suren Baghdasaryan , Ryan Roberts , Baolin Wang , Vlastimil Babka , Zi Yan , Mike Rapoport , Dave Hansen , Michal Hocko , Lorenzo Stoakes , Andrew Morton , Thomas Gleixner , Nico Pache , Dev Jain , "Liam R . Howlett" , Jens Axboe , linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, Ritesh Harjani , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Darrick J . Wong" , mcgrof@kernel.org, gost.dev@samsung.com, hch@lst.de, Pankaj Raghav References: <20250811084113.647267-1-kernel@pankajraghav.com> From: David Hildenbrand Content-Language: en-US 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/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11.08.25 11:43, Kiryl Shutsemau wrote: > On Mon, Aug 11, 2025 at 10:41:08AM +0200, Pankaj Raghav (Samsung) wrote: >> From: Pankaj Raghav >> >> Many places in the kernel need to zero out larger chunks, but the >> maximum segment we can zero out at a time by ZERO_PAGE is limited by >> PAGE_SIZE. >> >> This concern was raised during the review of adding Large Block Size support >> to XFS[2][3]. >> >> This is especially annoying in block devices and filesystems where >> multiple ZERO_PAGEs are attached to the bio in different bvecs. With multipage >> bvec support in block layer, it is much more efficient to send out >> larger zero pages as a part of single bvec. >> >> Some examples of places in the kernel where this could be useful: >> - blkdev_issue_zero_pages() >> - iomap_dio_zero() >> - vmalloc.c:zero_iter() >> - rxperf_process_call() >> - fscrypt_zeroout_range_inline_crypt() >> - bch2_checksum_update() >> ... >> >> Usually huge_zero_folio is allocated on demand, and it will be >> deallocated by the shrinker if there are no users of it left. At the moment, >> huge_zero_folio infrastructure refcount is tied to the process lifetime >> that created it. This might not work for bio layer as the completions >> can be async and the process that created the huge_zero_folio might no >> longer be alive. And, one of the main point that came during discussion >> is to have something bigger than zero page as a drop-in replacement. >> >> Add a config option PERSISTENT_HUGE_ZERO_FOLIO that will always allocate >> the huge_zero_folio, and disable the shrinker so that huge_zero_folio is >> never freed. >> This makes using the huge_zero_folio without having to pass any mm struct and does >> not tie the lifetime of the zero folio to anything, making it a drop-in >> replacement for ZERO_PAGE. >> >> I have converted blkdev_issue_zero_pages() as an example as a part of >> this series. I also noticed close to 4% performance improvement just by >> replacing ZERO_PAGE with persistent huge_zero_folio. >> >> I will send patches to individual subsystems using the huge_zero_folio >> once this gets upstreamed. >> >> Looking forward to some feedback. > > Why does it need to be compile-time? Maybe whoever needs huge zero page > would just call get_huge_zero_page()/folio() on initialization to get it > pinned? That's what v2 did, and this way here is cleaner. -- Cheers, David / dhildenb