PTRS_PER_PMD       40 arch/x86/include/asm/pgtable-3level_types.h #define PTRS_PER_PMD	512
PTRS_PER_PMD       42 arch/x86/include/asm/pgtable_64_types.h #define PTRS_PER_PMD	512
PTRS_PER_PMD       20 include/asm-generic/pgtable-nopmd.h #define PTRS_PER_PMD	1