page-writeback.c:(.text+0x6446): undefined reference to `____ilog2_NaN'

writeback-dirty-throttling-v7

  LD      vmlinux.o
  MODPOST vmlinux.o
WARNING: vmlinux.o(.text+0x1ba48): Section mismatch in reference from the function native_pagetable_reserve() to the function .init.text:memblock_x86_reserve_range()
The function native_pagetable_reserve() references
the function __init memblock_x86_reserve_range().
This is often because native_pagetable_reserve lacks a __init 
annotation or the annotation of memblock_x86_reserve_range is wrong.

  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  LD      init/built-in.o
  LD      .tmp_vmlinux1
mm/built-in.o: In function `calc_period_shift.part.10':
page-writeback.c:(.text+0x6458): undefined reference to `____ilog2_NaN'
make[4]: *** [.tmp_vmlinux1] Error 1