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    Subject[PATCH 0/7] HWPoison: Refactor get page interface
    Date
    Hi,

    following up on previous fix-ups an refactors, this patchset simplifies
    the get page interface and removes the MF_COUNT_INCREASED trick we have
    for soft offline.

    Please, note that this patchset is on top of [1] and [2].

    This patchset does three things:

    1) Drops MF_COUNT_INCREASED trick
    2) Refactors get page interface
    3) Places a common entry for grabbin a page from both hard offline
    and soft offline guarded by zone_pcp_{disable/enable}, so we do not
    have to drain pcplists by ourself and retry again.

    Note that the MF_COUNT_INCREASED trick was left because if get_hwpoison_page
    races with put_page (e.g:)

    CPU0 CPU1
    put_page (refcount decremented to 0)
    __put_single_page
    free_unref_page
    free_unref_page_prepare
    free_pcp_prepare
    free_pages_prepare soft_offline_page
    :page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP get_any_page
    get_hwpoison_page
    free_unref_page_commit
    free_one_page
    __free_one_page (place it in buddy)

    get_hwpoison_page sees that page has a refcount of 0, but since it was not placed
    in buddy yet we cannot really handle it.
    We now have a sort of maximum passes in get_any_page, so in case we race
    with either an allocation or a put_page, we retry again.

    After an off-list discussion with Naoya, he agreed to proceed.

    [1] https://patchwork.kernel.org/project/linux-mm/list/?series=364009
    [2] https://patchwork.kernel.org/project/linux-mm/list/?series=381903

    Naoya Horiguchi (3):
    mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED
    mm,hwpoison: remove MF_COUNT_INCREASED
    mm,hwpoison: remove flag argument from soft offline functions

    Oscar Salvador (4):
    mm,hwpoison: Refactor get_any_page
    mm,hwpoison: Drop pfn parameter
    mm,hwpoison: Disable pcplists before grabbing a refcount
    mm,hwpoison: Remove drain_all_pages from shake_page

    drivers/base/memory.c | 2 +-
    include/linux/mm.h | 9 +--
    mm/madvise.c | 19 +++--
    mm/memory-failure.c | 168 +++++++++++++++++-------------------------
    4 files changed, 85 insertions(+), 113 deletions(-)

    --
    2.26.2

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