linux-ext4 - Re: [PATCH 07/12] mm: Remove redundant pXd

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Message-ID: <20250603134814.GH386142@ziepe.ca>
Date: Tue, 3 Jun 2025 10:48:14 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Alistair Popple <apopple@...dia.com>
Cc: linux-mm@...ck.org, gerald.schaefer@...ux.ibm.com,
	dan.j.williams@...el.com, willy@...radead.org, david@...hat.com,
	linux-kernel@...r.kernel.org, nvdimm@...ts.linux.dev,
	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
	linux-xfs@...r.kernel.org, jhubbard@...dia.com, hch@....de,
	zhang.lyra@...il.com, debug@...osinc.com, bjorn@...nel.org,
	balbirs@...dia.com, lorenzo.stoakes@...cle.com,
	linux-arm-kernel@...ts.infradead.org, loongarch@...ts.linux.dev,
	linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
	linux-cxl@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	John@...ves.net
Subject: Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

On Thu, May 29, 2025 at 04:32:08PM +1000, Alistair Popple wrote:
> DAX was the only thing that created pmd_devmap and pud_devmap entries
> however it no longer does as DAX pages are now refcounted normally and
> pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap
> and pXd_trans_huge() is redundant and the former can be removed without
> changing behaviour as it will always be false.
> 
> Signed-off-by: Alistair Popple <apopple@...dia.com>
> ---
>  fs/dax.c                   |  5 ++---
>  include/linux/huge_mm.h    | 10 ++++------
>  include/linux/pgtable.h    |  2 +-
>  mm/hmm.c                   |  4 ++--
>  mm/huge_memory.c           | 30 +++++++++---------------------
>  mm/mapping_dirty_helpers.c |  4 ++--
>  mm/memory.c                | 15 ++++++---------
>  mm/migrate_device.c        |  2 +-
>  mm/mprotect.c              |  2 +-
>  mm/mremap.c                |  5 ++---
>  mm/page_vma_mapped.c       |  5 ++---
>  mm/pagewalk.c              |  8 +++-----
>  mm/pgtable-generic.c       |  7 +++----
>  mm/userfaultfd.c           |  4 ++--
>  mm/vmscan.c                |  3 ---
>  15 files changed, 40 insertions(+), 66 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason