tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
head:   2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d
commit: 0dc533504723599b41a4cefc6697379cddf55787 [14/19] sched: make schedstats helpers independent of fair sched class
config: m68k-buildonly-randconfig-r002-20210910 (attached as .config)
compiler: m68k-linux-gcc (GCC) 11.2.0
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://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?id=0dc533504723599b41a4cefc6697379cddf55787
        git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
        git fetch --no-tags peterz-queue sched/core
        git checkout 0dc533504723599b41a4cefc6697379cddf55787
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=m68k 

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

All warnings (new ones prefixed by >>):

   kernel/sched/fair.c: In function 'update_stats_wait_start_fair':
>> kernel/sched/fair.c:893:29: warning: variable 'p' set but not used [-Wunused-but-set-variable]
     893 |         struct task_struct *p = NULL;
         |                             ^
   kernel/sched/fair.c:892:34: warning: variable 'stats' set but not used [-Wunused-but-set-variable]
     892 |         struct sched_statistics *stats;
         |                                  ^~~~~
   kernel/sched/fair.c: In function 'update_stats_wait_end_fair':
   kernel/sched/fair.c:910:29: warning: variable 'p' set but not used [-Wunused-but-set-variable]
     910 |         struct task_struct *p = NULL;
         |                             ^
   kernel/sched/fair.c:909:34: warning: variable 'stats' set but not used [-Wunused-but-set-variable]
     909 |         struct sched_statistics *stats;
         |                                  ^~~~~
   kernel/sched/fair.c: In function 'update_stats_enqueue_sleeper_fair':
>> kernel/sched/fair.c:936:29: warning: variable 'tsk' set but not used [-Wunused-but-set-variable]
     936 |         struct task_struct *tsk = NULL;
         |                             ^~~
   kernel/sched/fair.c:935:34: warning: variable 'stats' set but not used [-Wunused-but-set-variable]
     935 |         struct sched_statistics *stats;
         |                                  ^~~~~
   kernel/sched/fair.c: At top level:
   kernel/sched/fair.c:5411:6: warning: no previous prototype for 'init_cfs_bandwidth' [-Wmissing-prototypes]
    5411 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
         |      ^~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c:11567:6: warning: no previous prototype for 'free_fair_sched_group' [-Wmissing-prototypes]
   11567 | void free_fair_sched_group(struct task_group *tg) { }
         |      ^~~~~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c:11569:5: warning: no previous prototype for 'alloc_fair_sched_group' [-Wmissing-prototypes]
   11569 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
         |     ^~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c:11574:6: warning: no previous prototype for 'online_fair_sched_group' [-Wmissing-prototypes]
   11574 | void online_fair_sched_group(struct task_group *tg) { }
         |      ^~~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c:11576:6: warning: no previous prototype for 'unregister_fair_sched_group' [-Wmissing-prototypes]
   11576 | void unregister_fair_sched_group(struct task_group *tg) { }
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/p +893 kernel/sched/fair.c

   888	
   889	static inline void
   890	update_stats_wait_start_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
   891	{
   892		struct sched_statistics *stats;
 > 893		struct task_struct *p = NULL;
   894	
   895		if (!schedstat_enabled())
   896			return;
   897	
   898		stats = __schedstats_from_se(se);
   899	
   900		if (entity_is_task(se))
   901			p = task_of(se);
   902	
   903		__update_stats_wait_start(rq_of(cfs_rq), p, stats);
   904	}
   905	
   906	static inline void
   907	update_stats_wait_end_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
   908	{
   909		struct sched_statistics *stats;
   910		struct task_struct *p = NULL;
   911	
   912		if (!schedstat_enabled())
   913			return;
   914	
   915		stats = __schedstats_from_se(se);
   916	
   917		/*
   918		 * When the sched_schedstat changes from 0 to 1, some sched se
   919		 * maybe already in the runqueue, the se->statistics.wait_start
   920		 * will be 0.So it will let the delta wrong. We need to avoid this
   921		 * scenario.
   922		 */
   923		if (unlikely(!schedstat_val(stats->wait_start)))
   924			return;
   925	
   926		if (entity_is_task(se))
   927			p = task_of(se);
   928	
   929		__update_stats_wait_end(rq_of(cfs_rq), p, stats);
   930	}
   931	
   932	static inline void
   933	update_stats_enqueue_sleeper_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
   934	{
   935		struct sched_statistics *stats;
 > 936		struct task_struct *tsk = NULL;
   937	
   938		if (!schedstat_enabled())
   939			return;
   940	
   941		stats = __schedstats_from_se(se);
   942	
   943		if (entity_is_task(se))
   944			tsk = task_of(se);
   945	
   946		__update_stats_enqueue_sleeper(rq_of(cfs_rq), tsk, stats);
   947	}
   948	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org