reproduce (this is a W=1 build):
        git remote add cifs git://git.samba.org/sfrench/cifs-2.6.git
        git fetch --no-tags cifs for-next
        git checkout f046d71e84e1e94cf23335129a27f5cfe3e8b75f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/smb/client/