reproduce (this is a W=1 build):
        # https://github.com/ceph/ceph-client/commit/e442fc60cf71f159f1138f01ad70d70305ff05d5
        git remote add ceph-client https://github.com/ceph/ceph-client.git
        git fetch --no-tags ceph-client wip-tls-tracing-parent-fix
        git checkout e442fc60cf71f159f1138f01ad70d70305ff05d5
        # 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 fs/ceph/