linux-kernel - Re: [PATCH 13/13] mm: Remove devmap related functions and page table bits

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Message-ID: <20240708113524.GD11567@willie-the-truck>
Date: Mon, 8 Jul 2024 12:35:25 +0100
From: Will Deacon <will@...nel.org>
To: Alistair Popple <apopple@...dia.com>
Cc: dan.j.williams@...el.com, vishal.l.verma@...el.com,
	dave.jiang@...el.com, logang@...tatee.com, bhelgaas@...gle.com,
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	peterx@...hat.com, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
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	linux-xfs@...r.kernel.org, jhubbard@...dia.com, hch@....de,
	david@...morbit.com
Subject: Re: [PATCH 13/13] mm: Remove devmap related functions and page table
 bits

On Thu, Jun 27, 2024 at 10:54:28AM +1000, Alistair Popple wrote:
> Now that DAX and all other reference counts to ZONE_DEVICE pages are
> managed normally there is no need for the special devmap PTE/PMD/PUD
> page table bits. So drop all references to these, freeing up a
> software defined page table bit on architectures supporting it.
> 
> Signed-off-by: Alistair Popple <apopple@...dia.com>
> ---
>  Documentation/mm/arch_pgtable_helpers.rst     |  6 +--
>  arch/arm64/Kconfig                            |  1 +-
>  arch/arm64/include/asm/pgtable-prot.h         |  1 +-
>  arch/arm64/include/asm/pgtable.h              | 24 +--------

Not only do you exclusively remove code, but you also give us back a
pte bit! What's not to like?

Acked-by: Will Deacon <will@...nel.org> # arm64

Will