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b=dN0ZAemYnR/7svCmpc2YMVy0ygxmA5qmYsXMLnQkjXGN8pxBM4Kzb3Q6QYrxUhlV/ V/A3GBUffRSnH01yXfnI1EjAwYPsTbieyN+FBS5n0fPYEgAf/HkJVuRsTAJN0KKVIk H0WrP7ntllmKDPrDb034BI7RcNRY+cGT1tBqtp9847MhF3WHERfeVBzCbRuPfKy7H0 nlVeyCzIy1aPOzqr0inqemLThwkUez9Z/Ec5JuFtdJILTAFlx/PSMRrTFEgikh+spS sBMQN2KLD2DLOvdZbRlAfiQRbmZZG57/gH2P1pE/Xm8SsncipN6YcGUj+pCeJOeesT /sSCaEO1GEt/A== Message-ID: Date: Thu, 5 Feb 2026 14:31:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv6 09/17] mm/sparse: Check memmap alignment for compound_info_has_mask() To: Kiryl Shutsemau , Andrew Morton , Muchun Song , Matthew Wilcox , Usama Arif , Frank van der Linden Cc: Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Zi Yan , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , Huacai Chen , WANG Xuerui , Palmer Dabbelt , Paul Walmsley , Albert Ou , Alexandre Ghiti , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org References: <20260202155634.650837-1-kas@kernel.org> <20260202155634.650837-10-kas@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: <20260202155634.650837-10-kas@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E0560C000A X-Stat-Signature: rxw4g6hd156njt98u8k981hcgzpsifg8 X-Rspam-User: X-HE-Tag: 1770298292-751635 X-HE-Meta: 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 pWshjzzx gwCz5v3963maFEY6VmQhR1awB4kqjj2ZtP9uNxMZ+gVkx4QBEfwBqZYSL4+wjgRJ4wtP9WPwA6ubW9BSKxKgghKaIiuaVjBbPGu7D4PIDIy7zhPKJliMvoGphy6QpnEsnZKT90NnHwcmoyXy3EIw1de7/La3PRewA6CkH/fG0LBsc9eLOmfR6KUzHE7g4Ku+SdBrMQa9EHnIMRAkfDUIqyEjHWKYCfzudZ+WaoeWEGf4FmGPI23d7qSx+s8hXB2TeRy5f152LJjQpzGtLRBkZS2QfrSlyl+dpv8tv77xTu2L2l9Y3lJIKuHvtfC2cdo+JBlVV26lrzQBVCwPMUt658FEirzefOZoRnTnN 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 2/2/26 16:56, Kiryl Shutsemau wrote: > If page->compound_info encodes a mask, it is expected that vmemmap to be > naturally aligned to the maximum folio size. > > Add a VM_BUG_ON() to check the alignment. > > Signed-off-by: Kiryl Shutsemau > Acked-by: Zi Yan > --- > mm/sparse.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/sparse.c b/mm/sparse.c > index b5b2b6f7041b..6c9b62607f3f 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -600,6 +600,13 @@ void __init sparse_init(void) > BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section))); > memblocks_present(); > > + if (compound_info_has_mask()) { > + unsigned long alignment; > + > + alignment = MAX_FOLIO_NR_PAGES * sizeof(struct page); > + VM_BUG_ON(!IS_ALIGNED((unsigned long) pfn_to_page(0), alignment)); No VM_BUG_ON. VM_WARN_ON_ONCE() should be good enough, no? As discussed in the other thread, is checking for MAX_FOLIO_NR_PAGES alignment sufficient? -- Cheers, David