From: Mike Rapoport <rppt@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Linu Cherian <linu.cherian@arm.com>,
Usama Arif <usama.arif@linux.dev>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC V2 02/14] mm: Add read-write accessors for vm_page_prot
Date: Sun, 17 May 2026 21:59:05 +0300 [thread overview]
Message-ID: <agoP-QlSeVgISjCw@kernel.org> (raw)
In-Reply-To: <20260513044547.4128549-3-anshuman.khandual@arm.com>
On Wed, May 13, 2026 at 10:15:35AM +0530, Anshuman Khandual wrote:
> Currently vma->vm_page_prot is safely read from and written to, without any
> locks with READ_ONCE() and WRITE_ONCE(). But with introduction of D128 page
> tables on arm64 platform, vm_page_prot grows to 128 bits which can't safely
> be handled with READ_ONCE() and WRITE_ONCE().
>
> Add read and write accessors for vm_page_prot like pgprot_[read|write]()
> which any platform can override when required, although still defaulting as
> READ_ONCE() and WRITE_ONCE(), thus preserving the functionality for others.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@kernel.org>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
> Changes in RFC V2:
>
> - Dropped _once from pgprot_[read|write]() callbacks per Mike
>
> include/linux/pgtable.h | 14 ++++++++++++++
> mm/huge_memory.c | 4 ++--
> mm/memory.c | 2 +-
> mm/migrate.c | 2 +-
> mm/mmap.c | 2 +-
> 5 files changed, 19 insertions(+), 5 deletions(-)
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2026-05-17 18:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 4:45 [RFC V2 00/14] arm64/mm: Enable 128 bit page table entries Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 01/14] mm: Abstract printing of pxd_val() Anshuman Khandual
2026-05-17 18:57 ` Mike Rapoport
2026-05-13 4:45 ` [RFC V2 02/14] mm: Add read-write accessors for vm_page_prot Anshuman Khandual
2026-05-17 18:59 ` Mike Rapoport [this message]
2026-05-13 4:45 ` [RFC V2 03/14] arm64/mm: Convert READ_ONCE() as pmdp_get() while accessing PMD Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 04/14] arm64/mm: Convert READ_ONCE() as pudp_get() while accessing PUD Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 05/14] arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 06/14] arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 07/14] arm64/mm: Route all pgtable reads via pxxval_get() Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 08/14] arm64/mm: Route all pgtable writes via pxxval_set() Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 09/14] arm64/mm: Route all pgtable atomics to central helpers Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 10/14] arm64/mm: Abstract printing of pxd_val() Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 11/14] arm64/mm: Override read-write accessors for vm_page_prot Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 13/14] arm64/mm: Add an abstraction level for tlbi_op Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 14/14] arm64/mm: Add initial support for FEAT_D128 page tables Anshuman Khandual
2026-05-13 9:39 ` [RFC V2 00/14] arm64/mm: Enable 128 bit page table entries Lorenzo Stoakes
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