From: Kiryl Shutsemau <kas@kernel.org>
To: Muchun Song <muchun.song@linux.dev>
Cc: "David Hildenbrand (Arm)" <david@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Usama Arif <usamaarif642@gmail.com>,
Frank van der Linden <fvdl@google.com>,
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,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCHv7 13/18] mm: Drop fake head checks
Date: Wed, 28 Oct 2026 13:04:38 +0000 [thread overview]
Message-ID: <auHxpuEHrpkvSFFi@thinkstation> (raw)
In-Reply-To: <7cb3dd91-f518-49b6-b311-9ec807b3c63b@linux.dev>
On Wed, Oct 28, 2026 at 10:38:22AM +0800, Muchun Song wrote:
> > Bootmem folios optimized in early boot get their tails mapped writable
> > and write protected later. Drop the write protect step.
>
> For bootmem folios, I don't think the RO mapping should be removed,
> because we are in the initialization stage of struct page.
> No one should touch those pages at this point; otherwise, they could
> encounter uninitialized struct page as well. This assumes no race
> exists during early boot.
>
> Since such a problem does not exist during the boot stage, why should
> we give up the protection that RO provides?
Agreed. Nothing does a lockless get on bootmem folios before hugetlb
takes them, so they can stay RO.
I will keep the pre-HVO write-protect and post the patch.
--
Kiryl Shutsemau / Kirill A. Shutemov
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WARNING: multiple messages have this Message-ID (diff)
From: Kiryl Shutsemau <kas@kernel.org>
To: Muchun Song <muchun.song@linux.dev>
Cc: "David Hildenbrand (Arm)" <david@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Usama Arif <usamaarif642@gmail.com>,
Frank van der Linden <fvdl@google.com>,
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,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCHv7 13/18] mm: Drop fake head checks
Date: Wed, 28 Oct 2026 13:04:38 +0000 [thread overview]
Message-ID: <auHxpuEHrpkvSFFi@thinkstation> (raw)
In-Reply-To: <7cb3dd91-f518-49b6-b311-9ec807b3c63b@linux.dev>
On Wed, Oct 28, 2026 at 10:38:22AM +0800, Muchun Song wrote:
> > Bootmem folios optimized in early boot get their tails mapped writable
> > and write protected later. Drop the write protect step.
>
> For bootmem folios, I don't think the RO mapping should be removed,
> because we are in the initialization stage of struct page.
> No one should touch those pages at this point; otherwise, they could
> encounter uninitialized struct page as well. This assumes no race
> exists during early boot.
>
> Since such a problem does not exist during the boot stage, why should
> we give up the protection that RO provides?
Agreed. Nothing does a lockless get on bootmem folios before hugetlb
takes them, so they can stay RO.
I will keep the pre-HVO write-protect and post the patch.
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2026-10-28 13:04 UTC|newest]
Thread overview: 122+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-27 19:42 [PATCHv7 RESEND 00/17] mm: Eliminate fake head pages from vmemmap optimization Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 01/18] mm: Move MAX_FOLIO_ORDER definition to mmzone.h Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 02/18] mm: Change the interface of prep_compound_tail() Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 03/18] mm: Rename the 'compound_head' field in the 'struct page' to 'compound_info' Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 04/18] mm: Move set/clear_compound_head() next to compound_head() Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 05/18] riscv/mm: Align vmemmap to maximal folio size Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-03-16 16:30 ` David Hildenbrand (Arm)
2026-03-16 16:30 ` David Hildenbrand (Arm)
2026-02-27 19:42 ` [PATCHv7 06/18] LoongArch/mm: " Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-03-16 16:31 ` David Hildenbrand (Arm)
2026-03-16 16:31 ` David Hildenbrand (Arm)
2026-02-27 19:42 ` [PATCHv7 07/18] mm: Rework compound_head() for power-of-2 sizeof(struct page) Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 08/18] mm/sparse: Check memmap alignment for compound_info_has_mask() Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-03-16 16:33 ` David Hildenbrand (Arm)
2026-03-16 16:33 ` David Hildenbrand (Arm)
2026-02-27 19:42 ` [PATCHv7 09/18] mm/hugetlb: Defer vmemmap population for bootmem hugepages Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-03-16 16:48 ` David Hildenbrand (Arm)
2026-03-16 16:48 ` David Hildenbrand (Arm)
2026-03-17 11:28 ` Kiryl Shutsemau
2026-03-17 11:28 ` Kiryl Shutsemau
2026-03-17 12:47 ` David Hildenbrand (Arm)
2026-03-17 12:47 ` David Hildenbrand (Arm)
2026-02-27 19:42 ` [PATCHv7 10/18] mm/hugetlb: Refactor code around vmemmap_walk Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 11/18] x86/vdso: Undefine CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP for vdso32 Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-03-16 16:49 ` David Hildenbrand (Arm)
2026-03-16 16:49 ` David Hildenbrand (Arm)
2026-02-27 19:42 ` [PATCHv7 12/18] mm/hugetlb: Remove fake head pages Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-03-05 10:39 ` Vlastimil Babka (SUSE)
2026-03-05 10:39 ` Vlastimil Babka (SUSE)
2026-03-16 17:01 ` David Hildenbrand (Arm)
2026-03-16 17:01 ` David Hildenbrand (Arm)
2026-03-17 11:47 ` [PATCHv7.1 " Kiryl Shutsemau (Meta)
2026-03-17 11:47 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 13/18] mm: Drop fake head checks Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-10-26 17:45 ` David Hildenbrand (Arm)
2026-10-26 17:45 ` David Hildenbrand (Arm)
2026-10-26 23:25 ` Kiryl Shutsemau
2026-10-26 23:25 ` Kiryl Shutsemau
2026-10-26 23:37 ` David Hildenbrand (Arm)
2026-10-26 23:37 ` David Hildenbrand (Arm)
2026-10-27 11:00 ` Peter Zijlstra
2026-10-27 11:00 ` Peter Zijlstra
2026-10-27 12:00 ` Kiryl Shutsemau
2026-10-27 12:00 ` Kiryl Shutsemau
2026-10-27 12:05 ` David Hildenbrand (Arm)
2026-10-27 12:05 ` David Hildenbrand (Arm)
2026-10-27 12:31 ` Kiryl Shutsemau
2026-10-27 12:31 ` Kiryl Shutsemau
2026-10-27 12:47 ` Peter Zijlstra
2026-10-27 12:47 ` Peter Zijlstra
2026-10-27 12:49 ` Peter Zijlstra
2026-10-27 12:49 ` Peter Zijlstra
2026-10-27 12:58 ` David Hildenbrand (Arm)
2026-10-27 12:58 ` David Hildenbrand (Arm)
2026-10-27 13:13 ` Muchun Song
2026-10-27 13:13 ` Muchun Song
2026-10-27 13:35 ` David Hildenbrand (Arm)
2026-10-27 13:35 ` David Hildenbrand (Arm)
2026-10-27 14:03 ` Muchun Song
2026-10-27 14:03 ` Muchun Song
2026-10-27 17:51 ` Kiryl Shutsemau
2026-10-27 17:51 ` Kiryl Shutsemau
2026-10-27 20:16 ` David Hildenbrand (Arm)
2026-10-27 20:16 ` David Hildenbrand (Arm)
2026-10-28 2:38 ` Muchun Song
2026-10-28 2:38 ` Muchun Song
2026-10-28 8:06 ` Peter Zijlstra
2026-10-28 8:06 ` Peter Zijlstra
2026-10-28 12:58 ` Kiryl Shutsemau
2026-10-28 12:58 ` Kiryl Shutsemau
2026-10-28 13:34 ` Peter Zijlstra
2026-10-28 13:34 ` Peter Zijlstra
2026-10-28 14:16 ` Kiryl Shutsemau
2026-10-28 14:16 ` Kiryl Shutsemau
2026-10-28 13:04 ` Kiryl Shutsemau [this message]
2026-10-28 13:04 ` Kiryl Shutsemau
2026-10-27 12:13 ` Peter Zijlstra
2026-10-27 12:13 ` Peter Zijlstra
2026-10-27 12:22 ` Kiryl Shutsemau
2026-10-27 12:22 ` Kiryl Shutsemau
2026-10-27 12:29 ` Peter Zijlstra
2026-10-27 12:29 ` Peter Zijlstra
2026-02-27 19:42 ` [PATCHv7 14/18] hugetlb: Remove VMEMMAP_SYNCHRONIZE_RCU Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 15/18] mm/hugetlb: Remove hugetlb_optimize_vmemmap_key static key Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 16/18] mm: Remove the branch from compound_head() Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` [PATCHv7 17/18] hugetlb: Update vmemmap_dedup.rst Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-27 21:08 ` Randy Dunlap
2026-02-27 21:08 ` Randy Dunlap
2026-03-02 3:10 ` Muchun Song
2026-03-02 3:10 ` Muchun Song
2026-03-02 10:56 ` [PATCHv7.1 " Kiryl Shutsemau (Meta)
2026-03-02 10:56 ` Kiryl Shutsemau (Meta)
2026-04-30 3:25 ` patchwork-bot+linux-riscv
2026-04-30 3:25 ` patchwork-bot+linux-riscv
2026-02-27 19:42 ` [PATCHv7 18/18] mm/slab: Use compound_head() in page_slab() Kiryl Shutsemau (Meta)
2026-02-27 19:42 ` Kiryl Shutsemau (Meta)
2026-02-28 23:01 ` [PATCHv7 RESEND 00/17] mm: Eliminate fake head pages from vmemmap optimization Andrew Morton
2026-02-28 23:01 ` Andrew Morton
2026-04-30 3:25 ` patchwork-bot+linux-riscv
2026-04-30 3:25 ` patchwork-bot+linux-riscv
-- strict thread matches above, loose matches on Subject: below --
2026-02-02 15:56 [PATCHv6 " Kiryl Shutsemau
2026-02-27 19:30 ` [PATCHv7 13/18] mm: Drop fake head checks Kiryl Shutsemau (Meta)
2026-02-27 19:30 ` Kiryl Shutsemau (Meta)
2026-04-30 3:25 ` patchwork-bot+linux-riscv
2026-04-30 3:25 ` patchwork-bot+linux-riscv
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