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    Subject[PATCH V3 0/4] arm64/mm: Enable memory hot remove
    Date
    This series enables memory hot remove on arm64 after fixing a memblock
    removal ordering problem in generic __remove_memory() and kernel page
    table race conditions on arm64. This is based on the following arm64
    working tree.

    git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core

    David had pointed out that the following patch is already in next/master
    (58b11e136dcc14358) and will conflict with the last patch here. Will fix
    the conflict once this series gets reviewed and agreed upon.

    Author: David Hildenbrand <david@redhat.com>
    Date: Wed Apr 10 11:02:27 2019 +1000

    mm/memory_hotplug: make __remove_pages() and arch_remove_memory() never fail

    All callers of arch_remove_memory() ignore errors. And we should really
    try to remove any errors from the memory removal path. No more errors are
    reported from __remove_pages(). BUG() in s390x code in case
    arch_remove_memory() is triggered. We may implement that properly later.
    WARN in case powerpc code failed to remove the section mapping, which is
    better than ignoring the error completely right now.

    Testing:

    Tested memory hot remove on arm64 for 4K, 16K, 64K page config options with
    all possible CONFIG_ARM64_VA_BITS and CONFIG_PGTABLE_LEVELS combinations. But
    build tested on non arm64 platforms.

    Changes in V3:

    - Implemented most of the suggestions from Mark Rutland for remove_pagetable()
    - Fixed applicable PGTABLE_LEVEL wrappers around pgtable page freeing functions
    - Replaced 'direct' with 'sparse_vmap' in remove_pagetable() with inverted polarity
    - Changed pointer names ('p' at end) and removed tmp from iterations
    - Perform intermediate TLB invalidation while clearing pgtable entries
    - Dropped flush_tlb_kernel_range() in remove_pagetable()
    - Added flush_tlb_kernel_range() in remove_pte_table() instead
    - Renamed page freeing functions for pgtable page and mapped pages
    - Used page range size instead of order while freeing mapped or pgtable pages
    - Removed all PageReserved() handling while freeing mapped or pgtable pages
    - Replaced XXX_index() with XXX_offset() while walking the kernel page table
    - Used READ_ONCE() while fetching individual pgtable entries
    - Taken overall init_mm.page_table_lock instead of just while changing an entry
    - Dropped previously added [pmd|pud]_index() which are not required anymore

    - Added a new patch to protect kernel page table race condtion for ptdump
    - Added a new patch from Mark Rutland to prevent huge-vmap with ptdump

    Changes in V2: (https://lkml.org/lkml/2019/4/14/5)

    - Added all received review and ack tags
    - Split the series from ZONE_DEVICE enablement for better review
    - Moved memblock re-order patch to the front as per Robin Murphy
    - Updated commit message on memblock re-order patch per Michal Hocko
    - Dropped [pmd|pud]_large() definitions
    - Used existing [pmd|pud]_sect() instead of earlier [pmd|pud]_large()
    - Removed __meminit and __ref tags as per Oscar Salvador
    - Dropped unnecessary 'ret' init in arch_add_memory() per Robin Murphy
    - Skipped calling into pgtable_page_dtor() for linear mapping page table
    pages and updated all relevant functions

    Changes in V1: (https://lkml.org/lkml/2019/4/3/28)

    Anshuman Khandual (3):
    mm/hotplug: Reorder arch_remove_memory() call in __remove_memory()
    arm64/mm: Hold memory hotplug lock while walking for kernel page table dump
    arm64/mm: Enable memory hot remove

    Mark Rutland (1):
    arm64/mm: Inhibit huge-vmap with ptdump

    arch/arm64/Kconfig | 3 +
    arch/arm64/mm/mmu.c | 215 ++++++++++++++++++++++++++++++++++++++++-
    arch/arm64/mm/ptdump_debugfs.c | 3 +
    mm/memory_hotplug.c | 3 +-
    4 files changed, 217 insertions(+), 7 deletions(-)

    --
    2.7.4

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