Hi Peter, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on vhost/linux-next] [also build test WARNING on linus/master v5.7-rc7] [cannot apply to kvm/linux-next tip/auto-latest linux/master next-20200526] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Peter-Xu/KVM-Dirty-ring-interfac... base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next config: x86_64-allyesconfig (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 3393cc4cebf9969db94dc424b7a2b6195589c33b) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): return false; ^~~~~ 1 warning generated. vim +1280 arch/x86/kvm/mmu/mmu.c 1269 1270 static struct kvm_memory_slot * 1271 gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, 1272 bool no_dirty_log) 1273 { 1274 struct kvm_memory_slot *slot; 1275 1276 slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); 1277 if (!slot || slot->flags & KVM_MEMSLOT_INVALID) 1278 return NULL; 1279 if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) 1281 1282 return slot; 1283 } 1284 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org