reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/staging.git/commit/?id=059f406972f3667040329c749c456120d9e05542
        git remote add bigeasy-staging https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/staging.git
        git fetch --no-tags bigeasy-staging futex_percpu_ref
        git checkout 059f406972f3667040329c749c456120d9e05542
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/