Re: [RFC PATCH 3/3] sched, rt: break out of load balancing if an RT task appears

[kbuild test robot <lkp@intel.com>]

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Hi Scott,

[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on tip/sched/core]
[also build test ERROR on tip/auto-latest linus/master linux/master v5.7-rc3 next-20200424]
[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/Scott-Wood/newidle_balance-latency-mitigation/20200428-202129
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 8f3d9f354286745c751374f5f1fcafee6b3f3136
config: openrisc-simple_smp_defconfig (attached as .config)
compiler: or1k-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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=openrisc 

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

All errors (new ones prefixed by >>):

   kernel/sched/fair.c: In function 'need_active_balance':
>> kernel/sched/fair.c:9385:6: error: implicit declaration of function 'rq_has_runnable_rt_task' [-Werror=implicit-function-declaration]
    9385 |  if (rq_has_runnable_rt_task(env->dst_rq)) {
         |      ^~~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c: In function 'balance_fair':
   kernel/sched/fair.c:6761:1: warning: control reaches end of non-void function [-Wreturn-type]
    6761 | }
         | ^
   cc1: some warnings being treated as errors

vim +/rq_has_runnable_rt_task +9385 kernel/sched/fair.c

  9379	
  9380	static int need_active_balance(struct lb_env *env, int *continue_balancing)
  9381	{
  9382		struct sched_domain *sd = env->sd;
  9383	
  9384		/* Run the realtime task now; load balance later. */
> 9385		if (rq_has_runnable_rt_task(env->dst_rq)) {
  9386			*continue_balancing = 0;
  9387			return 0;
  9388		}
  9389	
  9390		if (voluntary_active_balance(env))
  9391			return 1;
  9392	
  9393		return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
  9394	}
  9395	

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

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