tree: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git misc-next head: 43d923f7b1db8b930041fd2d3fe174991592a6da commit: 43d923f7b1db8b930041fd2d3fe174991592a6da [3/3] mm: don't call should_failslab() for !CONFIG_FAILSLAB config: um-x86_64_defconfig (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/axboe/linux-block.git/commit/?id=43d923f7b1db8b930041fd2d3fe174991592a6da git remote add axboe-block https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git git fetch --no-tags axboe-block misc-next git checkout 43d923f7b1db8b930041fd2d3fe174991592a6da # save the attached .config to linux build tree make W=1 ARCH=um SUBARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> mm/slab_common.c:1326:5: warning: no previous prototype for 'should_failslab' [-Wmissing-prototypes] 1326 | int should_failslab(struct kmem_cache *s, gfp_t gfpflags) | ^~~~~~~~~~~~~~~ vim +/should_failslab +1326 mm/slab_common.c 4f6923fbb352d1 Howard McLauchlan 2018-04-05 1325 4f6923fbb352d1 Howard McLauchlan 2018-04-05 @1326 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) :::::: The code at line 1326 was first introduced by commit :::::: 4f6923fbb352d126659cabe34806cff75c7b5ea0 mm: make should_failslab always available for fault injection :::::: TO: Howard McLauchlan :::::: CC: Linus Torvalds --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org