% ./tools/testing/kunit/kunit.py run --build_dir=/build/ext4-kunit Generating .config ... [22:04:12] Building KUnit Kernel ... /usr/projects/linux/kunit/arch/x86/um/user-offsets.c:20:10: fatal error: asm/syscalls_64.h: No such file or directory 20 | #include <asm/syscalls_64.h> | ^~~~~~~~~~~~~~~~~~~ compilation terminated. It appears that some file is not getting properly cleaned up by `make mrproper`. It works if you do `git clean -fdx` (That's not a real solution for most people). For more context see: https://groups.google.com/d/msg/kunit-dev/QmA27YEgEgI/hvS1kiz2CwAJ