Re: [PATCH 0/4] arm64/mm: Convert pgtable READ_ONCE() as pxdp_get()

[Anshuman Khandual]

On Mon, Sep 21, 2026 at 11:55:02AM +0100, Ryan Roberts wrote:
> On 03/09/2026 07:06, Anshuman Khandual wrote:
> > Route READ_ONCE() accesses on pgtable entries via level specific generic MM
> > pxdp_get() helpers which platforms could then override when required. These
> > accessors on arm64, will help in ensuring page table accesses are performed
> > in an atomic manner while reading 128 bit page table entries later. But for
> > now they just default to READ_ONCE(), thus preserving existing behaviour on
> > current D64 translation.
> > 
> > This is similar to generic MM, where all atomic accesses have already been
> > converted from READ_ONCE() into pgtable level specific accessors.
> > 
> > These are preparatory patches for D128 enablement, although standing their
> > own for D64 translation as well. These patches are split from earlier D128
> > V1 series. There are no functional changes here, and besides mm kselftests
> > do not show any regression.
> > 
> > https://lore.kernel.org/linux-mm/20260729122452.3797443-1-anshuman.khandual@xxxxxxx/
> > 
> > This series applies on v3.7-rc1 but after applying the following patches
> 
> I assume you meant v7.3-rc1 here?

Oops ! that's correct.

> 
> > related to pgtable entry print standardization posted earlier.
> > 
> > https://lore.kernel.org/linux-mm/20260831054331.625505-1-anshuman.khandual@xxxxxxx/
> 
> This applies.
> 
> > 
> > https://lore.kernel.org/linux-mm/20260901065454.1906343-1-anshuman.khandual@xxxxxxx/
> 
> This fails:
> ---8<---
> $ b4 shazam 20260901065454.1906343-1-anshuman.khandual@xxxxxxx
> Grabbing thread from
> lore.kernel.org/all/20260901065454.1906343-1-anshuman.khandual@xxxxxxx/t.mbox.gz
> Checking for newer revisions
> Grabbing search results from lore.kernel.org
>   Added from v3: 3 patches
>   Added from v2: 3 patches
> Analyzing 14 messages in the thread
> Looking for additional code-review trailers on lore.kernel.org
> Will use the latest revision: v3
> You can pick other revisions using the -vN flag
> Checking attestation on all messages, may take a moment...
> ---
>   ✓ [PATCH v3 1/2] arm64/mm: Move __check_safe_pte_update()
>   ✓ [PATCH v3 2/2] arm64/mm: Standardize printing for pgtable entries
>   ---
>   ✓ Signed: DKIM/arm.com
> ---
> Total patches: 2
> ---
> Applying: arm64/mm: Move __check_safe_pte_update()
> Applying: arm64/mm: Standardize printing for pgtable entries
> Patch failed at 0002 arm64/mm: Standardize printing for pgtable entries
> When you have resolved this problem, run "git am --continue".
> If you prefer to skip this patch, run "git am --skip" instead.
> To restore the original branch and stop patching, run "git am --abort".
> error: patch failed: arch/arm64/mm/fault.c:160
> error: arch/arm64/mm/fault.c: patch does not apply
> hint: Use 'git am --show-current-patch=diff' to see the failed patch
> ---8<---
> 
> And as a result I can't apply this series. Any tips?

May be this is based on older dependant patches.

The latest V3 does apply - although this series does not any more. 

https://lore.kernel.org/linux-mm/20260916044933.2689426-1-anshuman.khandual@xxxxxxx/

I will respin the series updating the commit message as suggested on
the other thread but probably with a hosted git branch for better
access - should have just done that earlier given multiple moving
pieces here.

> 
> Thanks,
> Ryan
> 
> 
> > 
> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Cc: Will Deacon <will@xxxxxxxxxx>
> > Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Cc: Lorenzo Stoakes <ljs@xxxxxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: David Hildenbrand <david@xxxxxxxxxx>
> > Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> > Cc: Linu Cherian <linu.cherian@xxxxxxx>
> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Cc: linux-mm@xxxxxxxxx
> > 
> > Anshuman Khandual (4):
> >   arm64/mm: Convert READ_ONCE() as pmdp_get() while accessing PMD
> >   arm64/mm: Convert READ_ONCE() as pudp_get() while accessing PUD
> >   arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D
> >   arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD
> > 
> >  arch/arm64/include/asm/pgtable.h |  6 ++--
> >  arch/arm64/mm/fault.c            |  8 ++---
> >  arch/arm64/mm/fixmap.c           |  6 ++--
> >  arch/arm64/mm/hugetlbpage.c      | 10 +++---
> >  arch/arm64/mm/kasan_init.c       | 18 +++++-----
> >  arch/arm64/mm/mmu.c              | 60 ++++++++++++++++----------------
> >  arch/arm64/mm/pageattr.c         |  8 ++---
> >  arch/arm64/mm/trans_pgd.c        | 14 ++++----
> >  8 files changed, 66 insertions(+), 64 deletions(-)
> > 
>