Hi Alexandre, [FYI, it's a private test report for your RFC patch.] [auto build test WARNING on tip/x86/mm] [also build test WARNING on v5.10-rc3 next-20201112] [cannot apply to tip/x86/core tip/x86/asm] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Alexandre-Chartre/x86-pti-Defer-... base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 1fcd009102ee02e217f2e7635ab65517d785da8e config: x86_64-randconfig-s022-20201110 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.3-107-gaf3512a6-dirty # https://github.com/0day-ci/linux/commit/0fcc7787f4670458b801ea103084c6494... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Alexandre-Chartre/x86-pti-Defer-CR3-switch-to-C-code/20201109-225007 git checkout 0fcc7787f4670458b801ea103084c6494227b89e # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; "sparse warnings: (new ones prefixed by >>)" vim +472 arch/x86/mm/pti.c 445 446 /* 447 * Clone the CPU_ENTRY_AREA and associated data into the user space visible 448 * page table. 449 */ 450 static void __init pti_clone_user_shared(void) 451 { 452 unsigned int cpu; 453 454 pti_clone_p4d(CPU_ENTRY_AREA_BASE); 455 456 for_each_possible_cpu(cpu) { 457 /* 458 * The SYSCALL64 entry code needs to be able to find the 459 * thread stack and needs one word of scratch space in which 460 * to spill a register. All of this lives in the TSS, in 461 * the sp1 and sp2 slots. 462 * 463 * This is done for all possible CPUs during boot to ensure 464 * that it's propagated to all mms. 465 */ 466 pti_clone_percpu_page(&per_cpu(cpu_tss_rw, cpu)); 467 468 /* 469 * Map fixed_percpu_data to get the stack canary. 470 */ 471 if (IS_ENABLED(CONFIG_STACKPROTECTOR)) 473 } 474 } 475 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org