linux-kernel - [PATCH v1 0/4] arm64: drop pfn_valid_within() and simplify pfn

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Date:   Tue, 20 Apr 2021 12:09:21 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        David Hildenbrand <david@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mike Rapoport <rppt@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Will Deacon <will@...nel.org>, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v1 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid()

From: Mike Rapoport <rppt@...ux.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 only boot tested on qemu-system-aarch64 so I'd really
appreciate memory stress tests on real hardware.

If this actually works we'll be one step closer to drop custom pfn_valid()
on arm64 altogether.

Changes since RFC
Link: https://lore.kernel.org/lkml/20210407172607.8812-1-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.

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   |  1 +
 arch/arm64/kvm/mmu.c            |  2 +-
 arch/arm64/mm/init.c            | 10 ++++++++--
 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, 54 insertions(+), 13 deletions(-)

base-commit: e49d033bddf5b565044e2abe4241353959bc9120
-- 
2.28.0