Hi Brendan, First bad commit (maybe != root cause): tree: https://android.googlesource.com/kernel/common android12-5.4 head: 150b1f5ee2833587c93b2931f3139b5b9d4ef616 commit: 5063607dbf3a4cef1150af59fd04611e4e9ddc09 [6/15] UPSTREAM: lib: enable building KUnit in lib/ config: x86_64-allyesconfig (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): git remote add android-common https://android.googlesource.com/kernel/common git fetch --no-tags android-common android12-5.4 git checkout 5063607dbf3a4cef1150af59fd04611e4e9ddc09 # save the attached .config to linux build tree make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): lib/kunit/test.c: In function 'kunit_vprintk_emit': 19 | return vprintk_emit(0, level, NULL, 0, fmt, args); | ^~~~~~ vim +19 lib/kunit/test.c ff82dbcb3e2cc5 Brendan Higgins 2019-09-23 16 ff82dbcb3e2cc5 Brendan Higgins 2019-09-23 17 static int kunit_vprintk_emit(int level, const char *fmt, va_list args) ff82dbcb3e2cc5 Brendan Higgins 2019-09-23 18 { ff82dbcb3e2cc5 Brendan Higgins 2019-09-23 @19 return vprintk_emit(0, level, NULL, 0, fmt, args); ff82dbcb3e2cc5 Brendan Higgins 2019-09-23 20 } ff82dbcb3e2cc5 Brendan Higgins 2019-09-23 21 :::::: The code at line 19 was first introduced by commit :::::: ff82dbcb3e2cc596f464302579fdf331f7422384 UPSTREAM: kunit: test: add KUnit test runner core :::::: TO: Brendan Higgins <brendanhiggins(a)google.com&gt; :::::: CC: Alexander Potapenko <glider(a)google.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org