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 lists.zx2c4.com (lists.zx2c4.com [165.227.139.114]) (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 093CCCA0FF7 for ; Fri, 29 Aug 2025 10:10:38 +0000 (UTC) Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 5559bbbf; Fri, 29 Aug 2025 10:06:51 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id 522047b5 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO) for ; Fri, 29 Aug 2025 10:06:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756462006; 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=lPHoMHV5vJS1QZV5L+lWiiTGuBUarel82A4quq5C180=; b=RoJHfS/+JAm4auyLzU9X62OhGbvNPBnuMgETM+OhhpEtswFtZp9yD0MM/36o5+GdcEPDmP Vu2ulEOgqXADaodM/Lcp7NhW8mCf1RKlE7ZiZiozz7/Szg3a1vyqsOVGhuYYxJ/lBBWrcO e0URhDT/XsFrgpZaQHSDJm91EPkq0WQ= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-358-Om-Oz2AYPDq6Ex_Rg6F-KA-1; Fri, 29 Aug 2025 06:06:26 -0400 X-MC-Unique: Om-Oz2AYPDq6Ex_Rg6F-KA-1 X-Mimecast-MFC-AGG-ID: Om-Oz2AYPDq6Ex_Rg6F-KA_1756461985 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-45a15f10f31so20261775e9.0 for ; Fri, 29 Aug 2025 03:06:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756461985; x=1757066785; 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=lPHoMHV5vJS1QZV5L+lWiiTGuBUarel82A4quq5C180=; b=Xj7wMrnYeuQuuZpRSzPdmWif4Rient04zEWkx4SrWpWvcsPHAHkXwqF3GvZVenBlNP odZhV2dDHuYe+4SPlIwiYz4p26H0Yf4EcUk2PN40u6aTE5eu2jk7T1hlQqRFXjDaxP80 sDhZnrl8D+TfiaBLIUxV2OFXLLyhESZ+n/im/JvaT27fV2TkgKnO+40aemTd6bge1gcg xIRP0V7gJAFWghTWJHUDTpov6AxjUif6uDq4p18H0rdwWo7A+5NdpAShzXtka2UIA6IL TGvfElUjDTad3p5Nio3H1iKaMfkXx5a/f1dyV9Z9GLCvj64yeJlJoVmtQ5s8d2oe46b6 bbkQ== X-Forwarded-Encrypted: i=1; AJvYcCXkWEQ7H178SQo/eMZAnJnHaH4TR8LFbMA8tjrcVGIhWtnhOfi68ZeJ0TlwTHbQp0ftrmxZ20EUgHg=@lists.zx2c4.com X-Gm-Message-State: AOJu0Yx93OR2zWTPe17IMAQSxQotSbKZhjxZGnd7inU40HyY/993Eb0g GU1KqYK7VQKvKUl/R7kK0Xb0yFl2Camfxa4z44X0rCZirI7RVDguIGnHPwFePI5lqdItSjGiXvE 0wHKx7AoRCP1mZ6citbcdRnt4EtL3Q6ts49C7ZItJOwApI5v4HpocKesXbtxwXA== X-Gm-Gg: ASbGncu46CbUJXsu6qBg8IROLhJby8GliFwqzwmTgRjE+rxzO99NP9DyMJ6LNZYxc+u CykusylMiJok7D5sMI9WzLaWE+jLEWmoKnohRLb4sbHfysYwLVM+hfXbp89oE/73CuKIlQGnODW O5aSz01B1tWk5TkOa8YdyhHPZ4k12ygoJYcfO3QsSkQrH+Ye4iqnmbcdzAe2CVl/lqtZob+Yfye 6Lj6tPizDeyi5DeoB0mXDVdBkqdnoWOfvM6Um0YHBW5lnPD2eQuhgQDSknZKlrzXYF4wy4m5geF 3MFT5QZcuhNP3DgmZD/WWFGCDORfEliBulHyo1gcRsJ8v63xi1uMq1o1OmCwd63DmErfifNBuE1 D6NQXpxVoFMjAvMzb1DZsa5Sui0opeAVhYyD4c/BGnONTK7lHzVjWq2p5+juO38Ey X-Received: by 2002:a05:6000:2082:b0:3ce:663a:c92f with SMTP id ffacd0b85a97d-3ce663af648mr3716847f8f.25.1756461984564; Fri, 29 Aug 2025 03:06:24 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG+cEIb1Z4u6pTtqsfT89DbTAZZhLHMJCnkgKmDWXX/Q7MNQLWv1cM4WZiGdQoi1AW0dJ7LMQ== X-Received: by 2002:a05:6000:2082:b0:3ce:663a:c92f with SMTP id ffacd0b85a97d-3ce663af648mr3716770f8f.25.1756461983963; Fri, 29 Aug 2025 03:06:23 -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 5b1f17b1804b1-45b74950639sm85846585e9.17.2025.08.29.03.06.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Aug 2025 03:06:23 -0700 (PDT) Message-ID: <547145e0-9b0e-40ca-8201-e94cc5d19356@redhat.com> Date: Fri, 29 Aug 2025 12:06:21 +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> 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: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: TnDfxjKRLlxe7pH6dv3NMWVCQ3N9AlVOgZp-TdvKlqw_1756461985 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" On 28.08.25 16:37, Lorenzo Stoakes wrote: > On Thu, Aug 28, 2025 at 12:01:10AM +0200, David Hildenbrand wrote: >> Let's reject them early, which in turn makes folio_alloc_gigantic() reject >> them properly. >> >> To avoid converting from order to nr_pages, let's just add MAX_FOLIO_ORDER >> and calculate MAX_FOLIO_NR_PAGES based on that. >> >> Reviewed-by: Zi Yan >> Acked-by: SeongJae Park >> Signed-off-by: David Hildenbrand > > Some nits, but overall LGTM so: > > Reviewed-by: Lorenzo Stoakes > >> --- >> include/linux/mm.h | 6 ++++-- >> mm/page_alloc.c | 5 ++++- >> 2 files changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 00c8a54127d37..77737cbf2216a 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -2055,11 +2055,13 @@ static inline long folio_nr_pages(const struct folio *folio) >> >> /* Only hugetlbfs can allocate folios larger than MAX_ORDER */ >> #ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE >> -#define MAX_FOLIO_NR_PAGES (1UL << PUD_ORDER) >> +#define MAX_FOLIO_ORDER PUD_ORDER >> #else >> -#define MAX_FOLIO_NR_PAGES MAX_ORDER_NR_PAGES >> +#define MAX_FOLIO_ORDER MAX_PAGE_ORDER >> #endif >> >> +#define MAX_FOLIO_NR_PAGES (1UL << MAX_FOLIO_ORDER) > > BIT()? I don't think we want to use BIT whenever we convert from order -> folio -- which is why we also don't do that in other code. BIT() is nice in the context of flags and bitmaps, but not really in the context of converting orders to pages. 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 ... :) > >> + >> /* >> * 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) >> { >> + 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. So I'll leave it as is I think. Thanks for all the review! -- Cheers David / dhildenb