reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?id=2060d8675bc5531f7e3b3f698c5c91045e8d45c6
        git remote add axboe-block https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
        git fetch --no-tags axboe-block rw_iter
        git checkout 2060d8675bc5531f7e3b3f698c5c91045e8d45c6
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 SHELL=/bin/bash drivers/usb/host/ drivers/usb/misc/ drivers/usb/mon/ fs/ocfs2/ fs/orangefs/ fs/pstore/ kernel/locking/ kernel/power/ security/selinux/ security/smack/