reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git/commit/?id=24e5f9a3c2f20d7a7c04b6d5cb2b4b7ec4f1a707
        git remote add mingo-tip https://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git
        git fetch --no-tags mingo-tip WIP.timers/core
        git checkout 24e5f9a3c2f20d7a7c04b6d5cb2b4b7ec4f1a707
        # 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 net/ipv4/