Hi Vivek, I love your patch! Perhaps something to improve: [auto build test WARNING on vhost/linux-next] [also build test WARNING on linus/master v5.6] [cannot apply to kvm/linux-next linux/master next-20200331] [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/Vivek-Goyal/kvm-x86-async_pf-Add... base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next config: x86_64-defconfig (attached as .config) compiler: gcc-7 (Debian 7.4.0-6) 7.4.0 reproduce: # save the attached .config to linux build tree make ARCH=x86_64 If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): In file included from include/uapi/linux/kvm_para.h:36:0, from include/linux/kvm_para.h:5, from arch/x86/kernel/cpu/mtrr/mtrr.c:39: arch/x86/include/asm/kvm_para.h: In function 'kvm_read_and_reset_pf_reason': return 0; ^ arch/x86/include/asm/kvm_para.h:124:20: note: declared here static inline void kvm_read_and_reset_pf_reason(struct kvm_apf_reason *reason) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ vim +/return +126 arch/x86/include/asm/kvm_para.h a4429e53c9b308 Wanpeng Li 2018-02-13 123 ace296186ca93c Vivek Goyal 2020-03-31 124 static inline void kvm_read_and_reset_pf_reason(struct kvm_apf_reason *reason) 631bc487822093 Gleb Natapov 2010-10-14 125 { 631bc487822093 Gleb Natapov 2010-10-14 @126 return 0; 631bc487822093 Gleb Natapov 2010-10-14 127 } d910f5c1064d7f Glauber Costa 2011-07-11 128 :::::: The code at line 126 was first introduced by commit :::::: 631bc4878220932fe67fc46fc7cf7cccdb1ec597 KVM: Handle async PF in a guest. :::::: TO: Gleb Natapov <gleb(a)redhat.com&gt; :::::: CC: Avi Kivity <avi(a)redhat.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org