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    Subject[PATCH v3 00/14] mm: page migration enhancement for thp
    Date
    From: Zi Yan <ziy@nvidia.com>

    Hi all,

    The patches are rebased on mmotm-2017-02-01-15-35 with feedbacks from
    Naoya Horiguchi's v2 patches.

    I fix a bug in zap_pmd_range() and include the fixes in Patches 1-3.
    The racy check in zap_pmd_range() can miss pmd_protnone and pmd_migration_entry,
    which leads to PTE page table not freed.

    In Patch 4, I move _PAGE_SWP_SOFT_DIRTY to bit 1. Because bit 6 (used in v2)
    can be set by some CPUs by mistake and the new swap entry format does not use
    bit 1-4.

    I also adjust two core migration functions, set_pmd_migration_entry() and
    remove_migration_pmd(), to use Kirill A. Shutemov's page_vma_mapped_walk()
    function. Patch 8 needs Kirill's comments, since I also add changes
    to his page_vma_mapped_walk() function with pmd_migration_entry handling.

    In Patch 8, I replace pmdp_huge_get_and_clear() with pmdp_huge_clear_flush()
    in set_pmd_migration_entry() to avoid data corruption after page migration.

    In Patch 9, I include is_pmd_migration_entry() in pmd_none_or_trans_huge_or_clear_bad().
    Otherwise, a pmd_migration_entry is treated as pmd_bad and cleared, which
    leads to deposited PTE page table not freed.

    I personally use this patchset with my customized kernel to test frequent
    page migrations by replacing page reclaim with page migration.
    The bugs fixed in Patches 1-3 and 8 was discovered while I am testing my kernel.
    I did a 16-hour stress test that has ~7 billion total page migrations.
    No error or data corruption was found.


    General description
    ===========================================

    This patchset enhances page migration functionality to handle thp migration
    for various page migration's callers:
    - mbind(2)
    - move_pages(2)
    - migrate_pages(2)
    - cgroup/cpuset migration
    - memory hotremove
    - soft offline

    The main benefit is that we can avoid unnecessary thp splits, which helps us
    avoid performance decrease when your applications handles NUMA optimization on
    their own.

    The implementation is similar to that of normal page migration, the key point
    is that we modify a pmd to a pmd migration entry in swap-entry like format.


    Any comments or advices are welcomed.

    Best Regards,
    Yan Zi

    Naoya Horiguchi (11):
    mm: x86: move _PAGE_SWP_SOFT_DIRTY from bit 7 to bit 1
    mm: mempolicy: add queue_pages_node_check()
    mm: thp: introduce separate TTU flag for thp freezing
    mm: thp: introduce CONFIG_ARCH_ENABLE_THP_MIGRATION
    mm: thp: enable thp migration in generic path
    mm: thp: check pmd migration entry in common path
    mm: soft-dirty: keep soft-dirty bits over thp migration
    mm: hwpoison: soft offline supports thp migration
    mm: mempolicy: mbind and migrate_pages support thp migration
    mm: migrate: move_pages() supports thp migration
    mm: memory_hotplug: memory hotremove supports thp migration

    Zi Yan (3):
    mm: thp: make __split_huge_pmd_locked visible.
    mm: thp: create new __zap_huge_pmd_locked function.
    mm: use pmd lock instead of racy checks in zap_pmd_range()

    arch/x86/Kconfig | 4 +
    arch/x86/include/asm/pgtable.h | 17 ++
    arch/x86/include/asm/pgtable_64.h | 2 +
    arch/x86/include/asm/pgtable_types.h | 10 +-
    arch/x86/mm/gup.c | 4 +-
    fs/proc/task_mmu.c | 37 +++--
    include/asm-generic/pgtable.h | 105 ++++--------
    include/linux/huge_mm.h | 36 ++++-
    include/linux/rmap.h | 1 +
    include/linux/swapops.h | 146 ++++++++++++++++-
    mm/Kconfig | 3 +
    mm/gup.c | 20 ++-
    mm/huge_memory.c | 302 +++++++++++++++++++++++++++++------
    mm/madvise.c | 2 +
    mm/memcontrol.c | 2 +
    mm/memory-failure.c | 31 ++--
    mm/memory.c | 33 ++--
    mm/memory_hotplug.c | 17 +-
    mm/mempolicy.c | 124 ++++++++++----
    mm/migrate.c | 66 ++++++--
    mm/mprotect.c | 6 +-
    mm/mremap.c | 2 +-
    mm/page_vma_mapped.c | 13 +-
    mm/pagewalk.c | 2 +
    mm/pgtable-generic.c | 3 +-
    mm/rmap.c | 21 ++-
    26 files changed, 770 insertions(+), 239 deletions(-)

    --
    2.11.0

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