reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/sforshee/linux.git/commit/?id=763b1048683d9063f889fd5c3783e420052abe6e
        git remote add sforshee https://git.kernel.org/pub/scm/linux/kernel/git/sforshee/linux.git
        git fetch --no-tags sforshee fscaps-vfsid
        git checkout 763b1048683d9063f889fd5c3783e420052abe6e
        make W=1 O=/tmp/kselftest headers
        make W=1 O=/tmp/kselftest -C tools/testing/selftests
        make W=1 O=/tmp/kselftest -C tools/testing/selftests/bpf