Hi Vincenzo, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: b10b8ad862118bf42c28a98b0f067619aadcfb23 commit: 89b94df9dfb16fe29f9d2085b0a98116dc34d814 [4594/9623] arm64: mte: Kconfig entry config: arm64-randconfig-s032-20200921 (attached as .config) compiler: aarch64-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # apt-get install sparse # sparse version: v0.6.2-201-g24bdaac6-dirty git checkout 89b94df9dfb16fe29f9d2085b0a98116dc34d814 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=arm64 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 >>) # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commi... git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git git fetch --no-tags linux-next master git checkout 89b94df9dfb16fe29f9d2085b0a98116dc34d814 vim +297 arch/arm64/kernel/mte.c 18ddbaa02b7a64f Catalin Marinas 2020-03-30 282 18ddbaa02b7a64f Catalin Marinas 2020-03-30 283 /* 18ddbaa02b7a64f Catalin Marinas 2020-03-30 284 * Copy MTE tags in another process' address space at 'addr' to/from tracer's 18ddbaa02b7a64f Catalin Marinas 2020-03-30 285 * iovec buffer. Return 0 on success. Inspired by ptrace_access_vm(). 18ddbaa02b7a64f Catalin Marinas 2020-03-30 286 */ 18ddbaa02b7a64f Catalin Marinas 2020-03-30 287 static int access_remote_tags(struct task_struct *tsk, unsigned long addr, 18ddbaa02b7a64f Catalin Marinas 2020-03-30 288 struct iovec *kiov, unsigned int gup_flags) 18ddbaa02b7a64f Catalin Marinas 2020-03-30 289 { 18ddbaa02b7a64f Catalin Marinas 2020-03-30 290 struct mm_struct *mm; 18ddbaa02b7a64f Catalin Marinas 2020-03-30 291 int ret; 18ddbaa02b7a64f Catalin Marinas 2020-03-30 292 18ddbaa02b7a64f Catalin Marinas 2020-03-30 293 mm = get_task_mm(tsk); 18ddbaa02b7a64f Catalin Marinas 2020-03-30 294 if (!mm) 18ddbaa02b7a64f Catalin Marinas 2020-03-30 295 return -EPERM; 18ddbaa02b7a64f Catalin Marinas 2020-03-30 296 18ddbaa02b7a64f Catalin Marinas 2020-03-30 @297 if (!tsk->ptrace || (current != tsk->parent) || 18ddbaa02b7a64f Catalin Marinas 2020-03-30 298 ((get_dumpable(mm) != SUID_DUMP_USER) && 18ddbaa02b7a64f Catalin Marinas 2020-03-30 299 !ptracer_capable(tsk, mm->user_ns))) { 18ddbaa02b7a64f Catalin Marinas 2020-03-30 300 mmput(mm); 18ddbaa02b7a64f Catalin Marinas 2020-03-30 301 return -EPERM; 18ddbaa02b7a64f Catalin Marinas 2020-03-30 302 } 18ddbaa02b7a64f Catalin Marinas 2020-03-30 303 18ddbaa02b7a64f Catalin Marinas 2020-03-30 304 ret = __access_remote_tags(mm, addr, kiov, gup_flags); 18ddbaa02b7a64f Catalin Marinas 2020-03-30 305 mmput(mm); 18ddbaa02b7a64f Catalin Marinas 2020-03-30 306 18ddbaa02b7a64f Catalin Marinas 2020-03-30 307 return ret; 18ddbaa02b7a64f Catalin Marinas 2020-03-30 308 } 18ddbaa02b7a64f Catalin Marinas 2020-03-30 309 :::::: The code at line 297 was first introduced by commit :::::: 18ddbaa02b7a64f4cf3e7e3d4b78b8b70481a17b arm64: mte: ptrace: Add PTRACE_{PEEK,POKE}MTETAGS support :::::: TO: Catalin Marinas <catalin.marinas(a)arm.com&gt; :::::: CC: Catalin Marinas <catalin.marinas(a)arm.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org