Re: [PATCH v4 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid()

From: Ard Biesheuvel <ardb@kernel.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	David Hildenbrand <david@redhat.com>,
	Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Mike Rapoport <rppt@linux.ibm.com>, Will Deacon <will@kernel.org>,
	kvmarm <kvmarm@lists.cs.columbia.edu>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH v4 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid()
Date: Wed, 12 May 2021 09:00:02 +0200	[thread overview]
Message-ID: <CAMj1kXFHLkmgZKEb8BtgGt6GQ93Qd+yv6NtiCvtgX0ex9wSeyw@mail.gmail.com> (raw)
In-Reply-To: <20210511100550.28178-1-rppt@kernel.org>

On Tue, 11 May 2021 at 12:05, Mike Rapoport <rppt@kernel.org> wrote:
>
> From: Mike Rapoport <rppt@linux.ibm.com>
>
> Hi,
>
> These patches aim to remove CONFIG_HOLES_IN_ZONE and essentially hardwire
> pfn_valid_within() to 1.
>
> The idea is to mark NOMAP pages as reserved in the memory map and restore
> the intended semantics of pfn_valid() to designate availability of struct
> page for a pfn.
>
> With this the core mm will be able to cope with the fact that it cannot use
> NOMAP pages and the holes created by NOMAP ranges within MAX_ORDER blocks
> will be treated correctly even without the need for pfn_valid_within.
>
> The patches are boot tested on qemu-system-aarch64.
>

Did you use EFI boot when testing this? The memory map is much more
fragmented in that case, so this would be a good data point.

> I beleive it would be best to route these via mmotm tree.
>
> v4:
> * rebase on v5.13-rc1
>
> v3: Link: https://lore.kernel.org/lkml/20210422061902.21614-1-rppt@kernel.org
> * Fix minor issues found by Anshuman
> * Freshen up the declaration of pfn_valid() to make it consistent with
>   pfn_is_map_memory()
> * Add more Acked-by and Reviewed-by tags, thanks Anshuman and David
>
> v2: Link: https://lore.kernel.org/lkml/20210421065108.1987-1-rppt@kernel.org
> * Add check for PFN overflow in pfn_is_map_memory()
> * Add Acked-by and Reviewed-by tags, thanks David.
>
> v1: Link: https://lore.kernel.org/lkml/20210420090925.7457-1-rppt@kernel.org
> * Add comment about the semantics of pfn_valid() as Anshuman suggested
> * Extend comments about MEMBLOCK_NOMAP, per Anshuman
> * Use pfn_is_map_memory() name for the exported wrapper for
>   memblock_is_map_memory(). It is still local to arch/arm64 in the end
>   because of header dependency issues.
>
> rfc: Link: https://lore.kernel.org/lkml/20210407172607.8812-1-rppt@kernel.org
>
> Mike Rapoport (4):
>   include/linux/mmzone.h: add documentation for pfn_valid()
>   memblock: update initialization of reserved pages
>   arm64: decouple check whether pfn is in linear map from pfn_valid()
>   arm64: drop pfn_valid_within() and simplify pfn_valid()
>
>  arch/arm64/Kconfig              |  3 ---
>  arch/arm64/include/asm/memory.h |  2 +-
>  arch/arm64/include/asm/page.h   |  3 ++-
>  arch/arm64/kvm/mmu.c            |  2 +-
>  arch/arm64/mm/init.c            | 14 +++++++++++++-
>  arch/arm64/mm/ioremap.c         |  4 ++--
>  arch/arm64/mm/mmu.c             |  2 +-
>  include/linux/memblock.h        |  4 +++-
>  include/linux/mmzone.h          | 11 +++++++++++
>  mm/memblock.c                   | 28 ++++++++++++++++++++++++++--
>  10 files changed, 60 insertions(+), 13 deletions(-)
>
>
> base-commit: 6efb943b8616ec53a5e444193dccf1af9ad627b5
> --
> 2.28.0
>