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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DA150CA0FF0 for ; Fri, 29 Aug 2025 16:25:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=2gVwH/YUrOi8KXVJsYmYvS6iUpfoMtdfJrraOJOUyx8=; b=GrLKO4HdlJIB8R C2cjtDqcLgQ55XRM32IskJTM9Po6mv5RXVcYWYXEBGfp+1/FOaoD0JFsJ0kj9etAL0yyzqRauKpvz lQjFY+vmZ/XTT4uXg02nefC38PeWoy0H76jycCEPLMul2d40wEc0OP4w/SXvkp3DT5hmQaZ8+8VNp 2XWyjcgs8V1LybpK+VyQt6IUF7bapSWZS7s2vyYra4oh1dJlPjaUvhNtHDpY2JZjPBv4yILFM1lgt GyF7stWFEME0xaL/GSVQhh07i1EmueDUi2uIOt/SrCsNCcwrHYCYodVAa2W5qvKuqxRVevBRfxoWA H1awlQo8pg7cJNxTm9jQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1us1ui-00000006O7e-2gDr; Fri, 29 Aug 2025 16:25:20 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uryrY-00000005lED-35K0 for linux-riscv@lists.infradead.org; Fri, 29 Aug 2025 13:09:54 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756472991; 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=GMW9HLrWQaKZG+KlEEwhYfHDFt7S0jSgL0MHJQucZHQ=; b=W77Nk43KwapZ/PN0ppI9OkDMdzLsFzdvdC/b/yuaZStPv6TCKRiXmhD2gEpACpEqlmSoKQ fy9xiqvIe1vDK8ht/CfBha8BW6l+aSX7H/TeOc7MddY2QJvJrVVLKSezxtvsS8nnv4OHpT nov6559jhkbkP27pl4yoFG8ggSJpcFc= 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-17-uzqG3Ga7NeekUMgW8snTKA-1; Fri, 29 Aug 2025 09:09:50 -0400 X-MC-Unique: uzqG3Ga7NeekUMgW8snTKA-1 X-Mimecast-MFC-AGG-ID: uzqG3Ga7NeekUMgW8snTKA_1756472989 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3cf48ec9fc1so629674f8f.0 for ; Fri, 29 Aug 2025 06:09:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756472989; x=1757077789; h=content-transfer-encoding:in-reply-to: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=GMW9HLrWQaKZG+KlEEwhYfHDFt7S0jSgL0MHJQucZHQ=; b=Uwk+2+egeSRlkH8NOqurSLk+Ery4Qtz27c12kmDXyy9kMr28as3MU3WnEyBWRtF+cQ 4wZHkGCKnHMY2HNzGAtRnkWHDJU65I/tTm2RsXAnrfMO0nczMisCQMATjP56TQFtgQUz O8N71sPpziaS1ZrwElSlTOkeK8yWcz/dT/UJwWpAd17PT/wBvLz11gbXRb4UfTG9qzT6 /qetfVomlJZ8jFb/Smhp8CTO9u7SLePafXhTopm00f4UHvZQztc+23PZmIiaJwVytwZC YBDdBz7ePWv8SjIwfLJ/s2r/PsC3JEo0u0P4/5cLgXaXvuD2Bq+2omEQLRoER1WgEFAA Ulaw== X-Forwarded-Encrypted: i=1; AJvYcCXKeMVSR70fvY08DdJ3gFDzJ/a6Wf9rFUThvjT5CPQbMG92ssVEd6k5FOowd7Ll+Gt8bLa02+55SpdqGA==@lists.infradead.org X-Gm-Message-State: AOJu0YzFGorvOZL4FICKbYvOJvpsfhV4/1rgThEtuRld7JPhVJOpitKw /6Wn7Is5yTDXtUvQw3yLQZ99T+9xXzMA1ZrzfPK7MWPKvFAQO3/B0SLd/iVeJK2oi9WLR9Ctdb0 IlRM5rWjzqZ3XTY1ZPTwZiE48+4TuMSwqsC6vuSK+zpeU/3HoLbGi0hX5Dr6pdKB678zgTA== X-Gm-Gg: ASbGnctkBXebl2AzneohfeLJAbYupr5XzdFXoQdk6ts3gJfTFoMmwfLc/knw/s3Er7L VXEprTOfmbhpbR4lDMOaOW56XrJaO9r/S9EZ/s39zxVqKyLw5H5zyL2ZF4Moc26CBh1Yd7B31vv v5jeblTw/5JmPh+oSTEmUCZuzraL7r4j2pbzlhgfUA9OXsNKkZCt4ga+RLBABC6/rJ7tlht7pY+ qDzLGKwigOKYxT43jYzcIPxf5OeJwhU3DM28ubf0DdsqYIi0g5+18we0vDsuY7XZdrmf0wiNKl5 TeKybbxO1qxLc0Tr9u6skNJ4t7wmSG9B56AX922PBv+dZ1HN9bufR/KDM/MJ8GbMBRvQqClsIEX QQH96yAP3IhfY/pfHaWBhw50b0OoPXSvwGZM69TVg9LPvhXc/due0BAqHBY8aSZem X-Received: by 2002:a05:6000:4023:b0:3d0:d6e6:5d96 with SMTP id ffacd0b85a97d-3d0d6e6642emr1463725f8f.38.1756472988509; Fri, 29 Aug 2025 06:09:48 -0700 (PDT) X-Google-Smtp-Source: AGHT+IE2EE1FdffCNgqV63lR4bEMYpCijk6Rt1WA7Ibu/9lrj3Iet7fHqrTgMv1xYGinJ39Wr3I/NQ== X-Received: by 2002:a05:6000:4023:b0:3d0:d6e6:5d96 with SMTP id ffacd0b85a97d-3d0d6e6642emr1463686f8f.38.1756472987991; Fri, 29 Aug 2025 06:09:47 -0700 (PDT) Received: from ?IPV6:2003:d8:2f1d:100:4f8e:bb13:c3c7:f854? (p200300d82f1d01004f8ebb13c3c7f854.dip0.t-ipconnect.de. [2003:d8:2f1d:100:4f8e:bb13:c3c7:f854]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3d12c90a01bsm906716f8f.31.2025.08.29.06.09.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Aug 2025 06:09:47 -0700 (PDT) Message-ID: <4f6e66a1-1747-402e-8f1a-f6b7783fc2e5@redhat.com> Date: Fri, 29 Aug 2025 15:09:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 06/36] mm/page_alloc: reject unreasonable folio/compound page sizes in alloc_contig_range_noprof() To: Lorenzo Stoakes Cc: linux-kernel@vger.kernel.org, Zi Yan , SeongJae Park , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Jens Axboe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Marco Elver , Marek Szyprowski , Michal Hocko , Mike Rapoport , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org References: <20250827220141.262669-1-david@redhat.com> <20250827220141.262669-7-david@redhat.com> <547145e0-9b0e-40ca-8201-e94cc5d19356@redhat.com> <34edaa0d-0d5f-4041-9a3d-fb5b2dd584e8@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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <34edaa0d-0d5f-4041-9a3d-fb5b2dd584e8@lucifer.local> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 8TVMr_fPrI8f88BBop37tZJtJcFXwc29WGclgcjiIW8_1756472989 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250829_060952_855963_DCA659EF X-CRM114-Status: GOOD ( 19.15 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org > > It seems a bit arbitrary, like we open-code this (at risk of making a mistake) > in some places but not others. [...] >> >> One could argue that maybe one would want a order_to_pages() helper (that >> could use BIT() internally), but I am certainly not someone that would >> suggest that at this point ... :) > > I mean maybe. > > Anyway as I said none of this is massively important, the open-coding here is > correct, just seems silly. Maybe we really want a ORDER_PAGES() and PAGES_ORDER(). But I mean, we also have PHYS_PFN() PFN_PHYS() and see how many "<< PAGE_SIZE" etc we are using all over the place. > >> >>> >>>> + >>>> /* >>>> * compound_nr() returns the number of pages in this potentially compound >>>> * page. compound_nr() can be called on a tail page, and is defined to >>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>>> index baead29b3e67b..426bc404b80cc 100644 >>>> --- a/mm/page_alloc.c >>>> +++ b/mm/page_alloc.c >>>> @@ -6833,6 +6833,7 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask) >>>> int alloc_contig_range_noprof(unsigned long start, unsigned long end, >>>> acr_flags_t alloc_flags, gfp_t gfp_mask) > > Funny btw th > >>>> { >>>> + const unsigned int order = ilog2(end - start); >>>> unsigned long outer_start, outer_end; >>>> int ret = 0; >>>> >>>> @@ -6850,6 +6851,9 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end, >>>> PB_ISOLATE_MODE_CMA_ALLOC : >>>> PB_ISOLATE_MODE_OTHER; >>>> >>>> + if (WARN_ON_ONCE((gfp_mask & __GFP_COMP) && order > MAX_FOLIO_ORDER)) >>>> + return -EINVAL; >>> >>> Possibly not worth it for a one off, but be nice to have this as a helper function, like: >>> >>> static bool is_valid_order(gfp_t gfp_mask, unsigned int order) >>> { >>> return !(gfp_mask & __GFP_COMP) || order <= MAX_FOLIO_ORDER; >>> } >>> >>> Then makes this: >>> >>> if (WARN_ON_ONCE(!is_valid_order(gfp_mask, order))) >>> return -EINVAL; >>> >>> Kinda self-documenting! >> >> I don't like it -- especially forwarding __GFP_COMP. >> >> is_valid_folio_order() to wrap the order check? Also not sure. > > OK, it's not a big deal. > > Can we have a comment explaining this though? As people might be confused > as to why we check this here and not elsewhere. I can add a comment. -- Cheers David / dhildenb _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv