[PATCH V4 0/3] arm64/mm/hotplug: Improve memory offline event notifier

[Anshuman Khandual]

This series brings three different changes to the only memory event notifier on
arm64 platform. These changes improve it's robustness while also enhancing debug
capabilities during potential memory offlining error conditions.

This applies on 5.9-rc7

Changes in V4:

- Dropped additional return in prevent_bootmem_remove_init() per Gavin
- Rearranged memory section loop in prevent_bootmem_remove_notifier() per Gavin
- Call out boot memory ranges for attempted offline or offline events

Changes in V3: (https://patchwork.kernel.org/project/linux-arm-kernel/list/?series=352717)

- Split the single patch into three patch series per Catalin
- Trigger changed from setup_arch() to early_initcall() per Catalin
- Renamed back memory_hotremove_notifier() as prevent_bootmem_remove_init()
- validate_bootmem_online() is now called from prevent_bootmem_remove_init() per Catalin
- Skip registering the notifier if validate_bootmem_online() returns negative

Changes in V2: (https://patchwork.kernel.org/patch/11732161/)

- Dropped all generic changes wrt MEM_CANCEL_OFFLINE reasons enumeration
- Dropped all related (processing MEM_CANCEL_OFFLINE reasons) changes on arm64
- Added validate_boot_mem_online_state() that gets called with early_initcall()
- Added CONFIG_MEMORY_HOTREMOVE check before registering memory notifier
- Moved notifier registration i.e memory_hotremove_notifier into setup_arch()

Changes in V1: (https://patchwork.kernel.org/project/linux-mm/list/?series=271237)

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Steve Capper <steve.capper@xxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Gavin Shan <gshan@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx

Anshuman Khandual (3):
  arm64/mm/hotplug: Register boot memory hot remove notifier earlier
  arm64/mm/hotplug: Enable MEM_OFFLINE event handling
  arm64/mm/hotplug: Ensure early memory sections are all online

 arch/arm64/mm/mmu.c | 101 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 97 insertions(+), 4 deletions(-)

-- 
2.20.1