reproduce (this is a W=1 build):
        git checkout linux/master
        b4 shazam https://lore.kernel.org/r/Zi9Ts1HcqiKzy9GX@gmail.com
        # 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 arch/x86/entry/vsyscall/