Hi Zhongkun,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Zhongkun-He/mm-replace-atomic_t-with-percpu_ref-in-mempolicy/20221205-001554
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20221204161432.2149375-1-hezhongkun.hzk%40bytedance.com
patch subject: [PATCH 0/3] mm: replace atomic_t with percpu_ref in mempolicy.
config: i386-randconfig-a013
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
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
        # https://github.com/intel-lab-lkp/linux/commit/ea5329aa9a0c20be63930f7c0fbb8aa238772851
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Zhongkun-He/mm-replace-atomic_t-with-percpu_ref-in-mempolicy/20221205-001554
        git checkout ea5329aa9a0c20be63930f7c0fbb8aa238772851
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

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

All errors (new ones prefixed by >>):

   In file included from drivers/char/mem.c:25:
   In file included from include/linux/shmem_fs.h:7:
>> include/linux/mempolicy.h:219:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
   }
   ^
   1 error generated.
--
   In file included from kernel/exit.c:38:
>> include/linux/mempolicy.h:219:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
   }
   ^
   kernel/exit.c:1839:13: warning: no previous prototype for function 'abort' [-Wmissing-prototypes]
   __weak void abort(void)
               ^
   kernel/exit.c:1839:8: note: declare 'static' if the function is not intended to be used outside of this translation unit
   __weak void abort(void)
          ^
          static 
   1 warning and 1 error generated.
--
   In file included from mm/shmem.c:38:
   In file included from include/linux/hugetlb.h:30:
>> include/linux/mempolicy.h:219:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
   }
   ^
   mm/shmem.c:1487:2: error: implicit declaration of function 'mpol_cond_put' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           mpol_cond_put(vma->vm_policy);
           ^
   2 errors generated.
--
   In file included from mm/hugetlb.c:15:
>> include/linux/mempolicy.h:219:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
   }
   ^
   mm/hugetlb.c:1249:2: error: implicit declaration of function 'mpol_cond_put' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           mpol_cond_put(mpol);
           ^
   mm/hugetlb.c:2324:2: error: implicit declaration of function 'mpol_cond_put' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           mpol_cond_put(mpol);
           ^
   mm/hugetlb.c:2360:2: error: implicit declaration of function 'mpol_cond_put' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           mpol_cond_put(mpol);
           ^
   4 errors generated.
--
   In file included from kernel/sched/fair.c:44:
>> include/linux/mempolicy.h:219:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
   }
   ^
   kernel/sched/fair.c:5794:6: warning: no previous prototype for function 'init_cfs_bandwidth' [-Wmissing-prototypes]
   void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
        ^
   kernel/sched/fair.c:5794:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
   ^
   static 
   kernel/sched/fair.c:12118:6: warning: no previous prototype for function 'free_fair_sched_group' [-Wmissing-prototypes]
   void free_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:12118:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void free_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:12120:5: warning: no previous prototype for function 'alloc_fair_sched_group' [-Wmissing-prototypes]
   int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
       ^
   kernel/sched/fair.c:12120:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
   ^
   static 
   kernel/sched/fair.c:12125:6: warning: no previous prototype for function 'online_fair_sched_group' [-Wmissing-prototypes]
   void online_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:12125:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void online_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:12127:6: warning: no previous prototype for function 'unregister_fair_sched_group' [-Wmissing-prototypes]
   void unregister_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:12127:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void unregister_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   5 warnings and 1 error generated.


vim +219 include/linux/mempolicy.h

   216	
   217	static inline bool mpol_tryget(struct mempolicy *pol)
   218	{
 > 219	}
   220	

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