reproduce (this is a W=1 build):
        # https://github.com/koverstreet/bcachefs/commit/54998105f6ef5d0c64d7986fd6f670d2b4f3bef4
        git remote add koverstreet-bcachefs https://github.com/koverstreet/bcachefs
        git fetch --no-tags koverstreet-bcachefs trace_sched_wakeup_backtrace
        git checkout 54998105f6ef5d0c64d7986fd6f670d2b4f3bef4

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=xtensa olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=xtensa SHELL=/bin/bash fs/bcachefs/