linux-kernel - Re: [PATCHv6 11/17] mm/hugetlb: Remove fake head pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <412359f2-ecfb-498a-9717-f0a442abd3f7@kernel.org>
Date: Sat, 7 Feb 2026 22:25:28 +0100
From: "David Hildenbrand (Arm)" <david@...nel.org>
To: Usama Arif <usamaarif642@...il.com>, Kiryl Shutsemau <kas@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Muchun Song <muchun.song@...ux.dev>, Matthew Wilcox <willy@...radead.org>,
 Frank van der Linden <fvdl@...gle.com>
Cc: Oscar Salvador <osalvador@...e.de>, Mike Rapoport <rppt@...nel.org>,
 Vlastimil Babka <vbabka@...e.cz>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Zi Yan <ziy@...dia.com>,
 Baoquan He <bhe@...hat.com>, Michal Hocko <mhocko@...e.com>,
 Johannes Weiner <hannes@...xchg.org>, Jonathan Corbet <corbet@....net>,
 Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>,
 Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley
 <paul.walmsley@...ive.com>, Albert Ou <aou@...s.berkeley.edu>,
 Alexandre Ghiti <alex@...ti.fr>, kernel-team@...a.com, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 loongarch@...ts.linux.dev, linux-riscv@...ts.infradead.org
Subject: Re: [PATCHv6 11/17] mm/hugetlb: Remove fake head pages

On 2/7/26 21:16, Usama Arif wrote:
> 
>> +
>>   int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
>>   				       int node, unsigned long headsize)
>>   {
>> +	unsigned long maddr, len, tail_pfn;
>> +	unsigned int order;
>>   	pte_t *pte;
>> -	unsigned long maddr;
>> +
>> +	len = end - addr;
>> +	order = ilog2(len * sizeof(struct page) / PAGE_SIZE);
> 
> 
> This doesnt work for ARM. For len = 32 (2MB contiguous-PTE hugetlb on arm64):
> ilog2(32 * 64 / 65536) = ilog2(2048 / 65536) = ilog2(0) which is undefined.

HVO should not be possible for that size, and we should never reach that 
point, no?

Remember that for HVO, the metadata must span at least two pages.

-- 
Cheers,

David