tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: e7bd807e8c9e37b0eef24e13df1f0619c39dc559 commit: 0cd39f4600ed4de859383018eb10f0f724900e1b locking/seqlock, headers: Untangle the spaghetti monster date: 1 year, 2 months ago config: i386-randconfig-r036-20210927 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0cd39f4600ed4de859383018eb10f0f724900e1b git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 0cd39f4600ed4de859383018eb10f0f724900e1b # save the attached .config to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> arch/x86/mm/highmem_32.c:66:13: warning: no previous prototype for 'set_highmem_pages_init' [-Wmissing-prototypes] 66 | void __init set_highmem_pages_init(void) | ^~~~~~~~~~~~~~~~~~~~~~ vim +/set_highmem_pages_init +66 arch/x86/mm/highmem_32.c 60e64d46a58236e3 arch/i386/mm/highmem.c Vivek Goyal 2005-06-25 65 867c5b5292583b1e arch/x86/mm/highmem_32.c Pekka Enberg 2009-03-03 @66 void __init set_highmem_pages_init(void) :::::: The code at line 66 was first introduced by commit :::::: 867c5b5292583b1e474cbbcb4c77f09bfca3903c x86: set_highmem_pages_init() cleanup :::::: TO: Pekka Enberg :::::: CC: Ingo Molnar --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org