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    Subject[PATCH 4.4 35/67] mm: update min_free_kbytes from khugepaged after core initialization
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jason Baron <jbaron@akamai.com>

    commit bc22af74f271ef76b2e6f72f3941f91f0da3f5f8 upstream.

    Khugepaged attempts to raise min_free_kbytes if its set too low.
    However, on boot khugepaged sets min_free_kbytes first from
    subsys_initcall(), and then the mm 'core' over-rides min_free_kbytes
    after from init_per_zone_wmark_min(), via a module_init() call.

    Khugepaged used to use a late_initcall() to set min_free_kbytes (such
    that it occurred after the core initialization), however this was
    removed when the initialization of min_free_kbytes was integrated into
    the starting of the khugepaged thread.

    The fix here is simply to invoke the core initialization using a
    core_initcall() instead of module_init(), such that the previous
    initialization ordering is restored. I didn't restore the
    late_initcall() since start_stop_khugepaged() already sets
    min_free_kbytes via set_recommended_min_free_kbytes().

    This was noticed when we had a number of page allocation failures when
    moving a workload to a kernel with this new initialization ordering. On
    an 8GB system this restores min_free_kbytes back to 67584 from 11365
    when CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
    CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
    CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.

    Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
    Signed-off-by: Jason Baron <jbaron@akamai.com>
    Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Acked-by: David Rientjes <rientjes@google.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    mm/page_alloc.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -6193,7 +6193,7 @@ int __meminit init_per_zone_wmark_min(vo
    setup_per_zone_inactive_ratio();
    return 0;
    }
    -module_init(init_per_zone_wmark_min)
    +core_initcall(init_per_zone_wmark_min)

    /*
    * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so

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