MIPS and ARM64 don't implement find_first_{zero}_bit in arch code and don't enable it in config. It leads to using find_next_bit() which is less efficient: It's beneficial to enable GENERIC_FIND_FIRST_BIT as this functionality is not new at all and well-tested. It provides more optimized code and saves .text memory: Alexander Lobakin (1): MIPS: enable GENERIC_FIND_FIRST_BIT Yury Norov (1): arm64: enable GENERIC_FIND_FIRST_BIT arch/arm64/Kconfig | 1 + arch/mips/Kconfig | 1 + 2 files changed, 2 insertions(+) -- 2.25.1