From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Usama Arif <usamaarif642@gmail.com>,
Kiryl Shutsemau <kas@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Muchun Song <muchun.song@linux.dev>,
Matthew Wilcox <willy@infradead.org>,
Frank van der Linden <fvdl@google.com>
Cc: Oscar Salvador <osalvador@suse.de>,
Mike Rapoport <rppt@kernel.org>, Vlastimil Babka <vbabka@suse.cz>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Zi Yan <ziy@nvidia.com>, Baoquan He <bhe@redhat.com>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Jonathan Corbet <corbet@lwn.net>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexandre Ghiti <alex@ghiti.fr>,
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
Subject: Re: [PATCHv6 11/17] mm/hugetlb: Remove fake head pages
Date: Sat, 7 Feb 2026 22:25:28 +0100 [thread overview]
Message-ID: <412359f2-ecfb-498a-9717-f0a442abd3f7@kernel.org> (raw)
In-Reply-To: <907ff793-9b02-4a22-a85e-2873246f6402@gmail.com>
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
next prev parent reply other threads:[~2026-02-07 21:25 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-02 15:56 [PATCHv6 00/17] mm: Eliminate fake head pages from vmemmap optimization Kiryl Shutsemau
2026-02-02 15:56 ` [PATCHv6 01/17] mm: Move MAX_FOLIO_ORDER definition to mmzone.h Kiryl Shutsemau
2026-02-07 20:20 ` Usama Arif
2026-02-10 15:01 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 02/17] mm: Change the interface of prep_compound_tail() Kiryl Shutsemau
2026-02-04 16:14 ` David Hildenbrand (arm)
2026-02-05 11:35 ` Kiryl Shutsemau
2026-02-05 11:58 ` David Hildenbrand (arm)
2026-02-10 15:06 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 03/17] mm: Rename the 'compound_head' field in the 'struct page' to 'compound_info' Kiryl Shutsemau
2026-02-04 16:14 ` David Hildenbrand (arm)
2026-02-10 15:09 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 04/17] mm: Move set/clear_compound_head() next to compound_head() Kiryl Shutsemau
2026-02-04 16:35 ` David Hildenbrand (arm)
2026-02-10 15:10 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 05/17] riscv/mm: Align vmemmap to maximal folio size Kiryl Shutsemau
2026-02-04 16:50 ` David Hildenbrand (arm)
2026-02-05 13:50 ` Kiryl Shutsemau
2026-02-05 13:54 ` David Hildenbrand (Arm)
2026-02-02 15:56 ` [PATCHv6 06/17] LoongArch/mm: " Kiryl Shutsemau
2026-02-04 16:56 ` David Hildenbrand (arm)
2026-02-05 12:56 ` David Hildenbrand (Arm)
2026-02-05 13:43 ` Kiryl Shutsemau
2026-02-05 13:52 ` David Hildenbrand (Arm)
2026-02-05 13:52 ` Kiryl Shutsemau
2026-02-05 13:57 ` David Hildenbrand (Arm)
2026-02-02 15:56 ` [PATCHv6 07/17] mm: Rework compound_head() for power-of-2 sizeof(struct page) Kiryl Shutsemau
2026-02-05 14:09 ` David Hildenbrand (Arm)
2026-02-07 20:19 ` Usama Arif
2026-02-10 15:40 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 08/17] mm: Make page_zonenum() use head page Kiryl Shutsemau
2026-02-04 3:40 ` Muchun Song
2026-02-05 13:10 ` David Hildenbrand (Arm)
2026-02-09 11:52 ` Kiryl Shutsemau
2026-02-10 15:57 ` Vlastimil Babka
2026-02-16 11:30 ` Kiryl Shutsemau
2026-02-15 23:13 ` Matthew Wilcox
2026-02-16 9:06 ` David Hildenbrand (Arm)
2026-02-16 11:20 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 09/17] mm/sparse: Check memmap alignment for compound_info_has_mask() Kiryl Shutsemau
2026-02-03 3:35 ` Muchun Song
2026-02-05 13:31 ` David Hildenbrand (Arm)
2026-02-05 13:58 ` David Hildenbrand (Arm)
2026-02-02 15:56 ` [PATCHv6 10/17] mm/hugetlb: Refactor code around vmemmap_walk Kiryl Shutsemau
2026-02-02 15:56 ` [PATCHv6 11/17] mm/hugetlb: Remove fake head pages Kiryl Shutsemau
2026-02-03 9:50 ` Muchun Song
2026-02-06 9:14 ` David Hildenbrand (Arm)
2026-02-06 9:36 ` David Hildenbrand (Arm)
2026-02-07 20:16 ` Usama Arif
2026-02-07 21:25 ` David Hildenbrand (Arm) [this message]
2026-02-07 22:50 ` Usama Arif
2026-02-02 15:56 ` [PATCHv6 12/17] mm: Drop fake head checks Kiryl Shutsemau
2026-02-06 9:41 ` David Hildenbrand (Arm)
2026-02-10 16:18 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 13/17] hugetlb: Remove VMEMMAP_SYNCHRONIZE_RCU Kiryl Shutsemau
2026-02-06 9:42 ` David Hildenbrand (Arm)
2026-02-02 15:56 ` [PATCHv6 14/17] mm/hugetlb: Remove hugetlb_optimize_vmemmap_key static key Kiryl Shutsemau
2026-02-06 9:42 ` David Hildenbrand (Arm)
2026-02-02 15:56 ` [PATCHv6 15/17] mm: Remove the branch from compound_head() Kiryl Shutsemau
2026-02-06 10:23 ` David Hildenbrand (Arm)
2026-02-10 16:42 ` Vlastimil Babka
2026-02-02 15:56 ` [PATCHv6 16/17] hugetlb: Update vmemmap_dedup.rst Kiryl Shutsemau
2026-02-06 10:35 ` David Hildenbrand (Arm)
2026-02-02 15:56 ` [PATCHv6 17/17] mm/slab: Use compound_head() in page_slab() Kiryl Shutsemau
2026-02-04 3:39 ` Muchun Song
2026-02-06 10:42 ` David Hildenbrand (Arm)
2026-02-10 16:45 ` Vlastimil Babka
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