Hi Minchan,

I love your patch! Perhaps something to improve:

[auto build test WARNING on m68k/for-next]
[also build test WARNING on powerpc/next s390/features linus/master v5.6-rc2 next-20200220]
[cannot apply to arm64/for-next/core tip/x86/asm arm/for-next hp-parisc/for-next]
[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/Minchan-Kim/introduce-memory-hinting-API-for-external-process/20200220-225155
base:   https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git for-next
config: nds32-randconfig-a001-20200220 (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=9.2.0 make.cross ARCH=nds32 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from arch/nds32/include/uapi/asm/unistd.h:10,
                    from arch/nds32/include/asm/unistd.h:6,
                    from arch/nds32/kernel/vdso/sigreturn.S:6:
>> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined
     858 | #define __NR_pidfd_getfd 439
         | 
   include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition
     856 | #define __NR_pidfd_getfd 438
         | 
--
   In file included from arch/nds32/include/uapi/asm/unistd.h:10,
                    from arch/nds32/include/asm/unistd.h:6,
                    from <stdin>:2:
>> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined
     858 | #define __NR_pidfd_getfd 439
         | 
   include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition
     856 | #define __NR_pidfd_getfd 438
         | 
   <stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
>> <stdin>:1520:2: warning: #warning syscall process_madvise not implemented [-Wcpp]
--
   In file included from arch/nds32/include/uapi/asm/unistd.h:10,
                    from arch/nds32/include/asm/unistd.h:6,
                    from <stdin>:2:
>> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined
     858 | #define __NR_pidfd_getfd 439
         | 
   include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition
     856 | #define __NR_pidfd_getfd 438
         | 
   <stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
>> <stdin>:1520:2: warning: #warning syscall process_madvise not implemented [-Wcpp]
   16 real  2 user  4 sys  39.01% cpu 	make modules_prepare
--
   In file included from arch/nds32/include/uapi/asm/unistd.h:10,
                    from arch/nds32/include/asm/unistd.h:6,
                    from <stdin>:2:
>> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined
     858 | #define __NR_pidfd_getfd 439
         | 
   include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition
     856 | #define __NR_pidfd_getfd 438
         | 
   <stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
>> <stdin>:1520:2: warning: #warning syscall process_madvise not implemented [-Wcpp]
   In file included from arch/nds32/include/uapi/asm/unistd.h:10,
                    from arch/nds32/include/asm/unistd.h:6,
                    from arch/nds32/kernel/vdso/sigreturn.S:6:
>> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined
     858 | #define __NR_pidfd_getfd 439
         | 
   include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition
     856 | #define __NR_pidfd_getfd 438
         | 
   In file included from arch/nds32/include/uapi/asm/unistd.h:10,
                    from arch/nds32/include/asm/unistd.h:6,
                    from arch/nds32/kernel/vdso/gettimeofday.c:11:
>> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined
     858 | #define __NR_pidfd_getfd 439
         | 
   include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition
     856 | #define __NR_pidfd_getfd 438
         | 
   17 real  4 user  6 sys  59.28% cpu 	make prepare

vim +/__NR_pidfd_getfd +858 include/uapi/asm-generic/unistd.h

   853	
   854	#define __NR_openat2 437
   855	__SYSCALL(__NR_openat2, sys_openat2)
   856	#define __NR_pidfd_getfd 438
   857	__SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd)
 > 858	#define __NR_pidfd_getfd 439
   859	__SYSCALL(__NR_process_madvise, sys_process_madvise)
   860	

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