tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git master head: 7b18c2d1930b99fc2acd4b9499a55f51df2a6678 commit: dde56e52f55a3bed98d1b02d83ab4376c7e152b4 [387/476] x86/mm/tlb: Flush remote and local TLBs concurrently config: x86_64-randconfig-a003-20210215 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476) 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 # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?... git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git git fetch --no-tags peterz-queue master git checkout dde56e52f55a3bed98d1b02d83ab4376c7e152b4 # 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: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arch/x86/kernel/paravirt.c:111:13: warning: no previous prototype for function 'native_pv_lock_init' [-Wmissing-prototypes] void __init native_pv_lock_init(void) ^ arch/x86/kernel/paravirt.c:111:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __init native_pv_lock_init(void) ^ static .mmu.flush_tlb_others = native_flush_tlb_others, ^ 1 warning and 1 error generated. vim +/native_flush_tlb_others +338 arch/x86/kernel/paravirt.c 5c83511bdb9832 Juergen Gross 2018-08-28 333 5c83511bdb9832 Juergen Gross 2018-08-28 334 /* Mmu ops. */ 2faf153bb7346b Thomas Gleixner 2020-04-21 335 .mmu.flush_tlb_user = native_flush_tlb_local, 5c83511bdb9832 Juergen Gross 2018-08-28 336 .mmu.flush_tlb_kernel = native_flush_tlb_global, 5c83511bdb9832 Juergen Gross 2018-08-28 337 .mmu.flush_tlb_one_user = native_flush_tlb_one_user, 5c83511bdb9832 Juergen Gross 2018-08-28 @338 .mmu.flush_tlb_others = native_flush_tlb_others, 5c83511bdb9832 Juergen Gross 2018-08-28 339 .mmu.tlb_remove_table = 5c83511bdb9832 Juergen Gross 2018-08-28 340 (void (*)(struct mmu_gather *, void *))tlb_remove_page, 5c83511bdb9832 Juergen Gross 2018-08-28 341 fdc0269e8958a1 Juergen Gross 2018-08-28 342 .mmu.exit_mmap = paravirt_nop, fdc0269e8958a1 Juergen Gross 2018-08-28 343 :::::: The code at line 338 was first introduced by commit :::::: 5c83511bdb9832c86be20fb86b783356e2f58062 x86/paravirt: Use a single ops structure :::::: TO: Juergen Gross <jgross(a)suse.com&gt; :::::: CC: Thomas Gleixner <tglx(a)linutronix.de&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org