Hi,
On linux-next cd tools/testing/selftests/futex && make clean -j 32 gives warning make[1]: warning: jobserver unavailable: using -j1. Add '+' to parent make rule. The full logs with with different reproduction steps can be found here: https://storage.staging.kernelci.org/next/master/next-20220310/x86_64/x86_64.... Usually this type of warning shouldn't come when $MAKE is being used instead of make in Makefile.
Maybe `define CLEAN` inside override construct defined in parent makefile is not getting jobsever information when child make process executes. I've enabled verbose mode and tried with other makefile flags (-p, -d etc) as well. Documentation mentions that if make is unable to identify the child process correctly, this warning will appear.
Please share if you have any thoughts on it.