Hi Vincenzo,

I love your patch! Yet something to improve:

[auto build test ERROR on next-20210125]
[cannot apply to arm64/for-next/core xlnx/master arm/for-next soc/for-next kvmarm/next linus/master hnaz-linux-mm/master v5.11-rc6 v5.11-rc5 v5.11-rc4 v5.11-rc6]
[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/Vincenzo-Frascino/arm64-ARMv8-5-A-MTE-Add-async-mode-support/20210209-080907
base:    59fa6a163ffabc1bf25c5e0e33899e268a96d3cc
config: x86_64-randconfig-s021-20210209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-215-g0fb77bb6-dirty
        # https://github.com/0day-ci/linux/commit/93bd347e4877e3616f7db64f488ebb469718dd68
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Vincenzo-Frascino/arm64-ARMv8-5-A-MTE-Add-async-mode-support/20210209-080907
        git checkout 93bd347e4877e3616f7db64f488ebb469718dd68
        # 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@intel.com>

All errors (new ones prefixed by >>):

   ld: mm/kasan/report.o: in function `end_report':
>> mm/kasan/report.c:90: undefined reference to `kasan_flag_async'
>> ld: mm/kasan/report.c:90: undefined reference to `kasan_flag_async'


vim +90 mm/kasan/report.c

    87	
    88	static void end_report(unsigned long *flags, unsigned long addr)
    89	{
  > 90		if (!kasan_flag_async)
    91			trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
    92		pr_err("==================================================================\n");
    93		add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
    94		spin_unlock_irqrestore(&report_lock, *flags);
    95		if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) {
    96			/*
    97			 * This thread may hit another WARN() in the panic path.
    98			 * Resetting this prevents additional WARN() from panicking the
    99			 * system on this thread.  Other threads are blocked by the
   100			 * panic_mutex in panic().
   101			 */
   102			panic_on_warn = 0;
   103			panic("panic_on_warn set ...\n");
   104		}
   105	#ifdef CONFIG_KASAN_HW_TAGS
   106		if (kasan_flag_panic)
   107			panic("kasan.fault=panic set ...\n");
   108	#endif
   109		kasan_enable_current();
   110	}
   111	

---
0-DAY CI Kernel Test Service, Intel Corporation
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