Re: [PATCH v4 12/13] sched: Attempt to fix rt/dl load balancing via chain level balance

From: kernel test robot
Date: Thu Jun 01 2023 - 10:19:47 EST

Hi John,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on tip/locking/core tip/master tip/auto-latest linus/master v6.4-rc4 next-20230601]
[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#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/John-Stultz/sched-Unify-runtime-accounting-across-classes/20230601-140200
base: tip/sched/core
patch link: https://lore.kernel.org/r/20230601055846.2349566-13-jstultz%40google.com
patch subject: [PATCH v4 12/13] sched: Attempt to fix rt/dl load balancing via chain level balance
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230601/202306011700.Ej6S3znC-lkp@xxxxxxxxx/config)
compiler: m68k-linux-gcc (GCC) 12.3.0
reproduce (this is a W=1 build):
mkdir -p ~/bin
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/82593266398c6feaed3ed5ec458986d8e16b6b74
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review John-Stultz/sched-Unify-runtime-accounting-across-classes/20230601-140200
git checkout 82593266398c6feaed3ed5ec458986d8e16b6b74
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=m68k olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash kernel/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306011700.Ej6S3znC-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> kernel/sched/core.c:3838:6: warning: no previous prototype for 'push_task_chain' [-Wmissing-prototypes]
3838 | void push_task_chain(struct rq *rq, struct rq *dst_rq, struct task_struct *task)
| ^~~~~~~~~~~~~~~
kernel/sched/core.c: In function 'push_task_chain':
kernel/sched/core.c:3858:42: error: 'struct rq' has no member named 'cpu'
3858 | set_task_cpu(task, dst_rq->cpu);
| ^~
kernel/sched/core.c: At top level:
>> kernel/sched/core.c:3870:21: warning: no previous prototype for 'find_exec_ctx' [-Wmissing-prototypes]
3870 | struct task_struct *find_exec_ctx(struct rq *rq, struct task_struct *p)
| ^~~~~~~~~~~~~
>> kernel/sched/core.c:3898:5: warning: no previous prototype for 'pushable_chain' [-Wmissing-prototypes]
3898 | int pushable_chain(struct rq *rq, struct task_struct *p, int cpu)
| ^~~~~~~~~~~~~~
kernel/sched/core.c:3930:6: warning: no previous prototype for 'ttwu_proxy_skip_wakeup' [-Wmissing-prototypes]
3930 | bool ttwu_proxy_skip_wakeup(struct rq *rq, struct task_struct *p)
| ^~~~~~~~~~~~~~~~~~~~~~
kernel/sched/core.c: In function 'proxy_migrate_task':
kernel/sched/core.c:6835:35: error: 'struct task_struct' has no member named 'wake_cpu'; did you mean 'wake_q'?
6835 | int wake_cpu = p->wake_cpu;
| ^~~~~~~~
| wake_q
kernel/sched/core.c:6851:20: error: 'struct task_struct' has no member named 'wake_cpu'; did you mean 'wake_q'?
6851 | p->wake_cpu = wake_cpu;
| ^~~~~~~~
| wake_q
kernel/sched/core.c:6854:15: error: 'struct rq' has no member named 'balance_callback'
6854 | if (rq->balance_callback)
| ^~


vim +/push_task_chain +3838 kernel/sched/core.c

3837
> 3838 void push_task_chain(struct rq *rq, struct rq *dst_rq, struct task_struct *task)
3839 {
3840 struct task_struct *owner;
3841
3842 lockdep_assert_rq_held(rq);
3843 lockdep_assert_rq_held(dst_rq);
3844
3845 BUG_ON(!task_queued_on_rq(rq, task));
3846 BUG_ON(task_current_selected(rq, task));
3847
3848 while (task) {
3849 if (!task_queued_on_rq(rq, task) || task_current_selected(rq, task))
3850 break;
3851
3852 if (task_is_blocked(task))
3853 owner = __mutex_owner(task->blocked_on);
3854 else
3855 owner = NULL;
3856
3857 deactivate_task(rq, task, 0);
> 3858 set_task_cpu(task, dst_rq->cpu);
3859 activate_task(dst_rq, task, 0);
3860 if (task == owner)
3861 break;
3862 task = owner;
3863 }
3864 }
3865
3866 /*
3867 * Returns the unblocked task at the end of the blocked chain starting with p
3868 * if that chain is composed entirely of tasks enqueued on rq, or NULL otherwise.
3869 */
> 3870 struct task_struct *find_exec_ctx(struct rq *rq, struct task_struct *p)
3871 {
3872 struct task_struct *exec_ctx, *owner;
3873 struct mutex *mutex;
3874
3875 lockdep_assert_rq_held(rq);
3876
3877 for (exec_ctx = p; task_is_blocked(exec_ctx) && !task_on_cpu(rq, exec_ctx);
3878 exec_ctx = owner) {
3879 mutex = exec_ctx->blocked_on;
3880 owner = __mutex_owner(mutex);
3881 if (owner == exec_ctx)
3882 break;
3883
3884 if (!task_queued_on_rq(rq, owner) || task_current_selected(rq, owner)) {
3885 exec_ctx = NULL;
3886 break;
3887 }
3888 }
3889 return exec_ctx;
3890 }
3891
3892 /*
3893 * Returns:
3894 * 1 if chain is pushable and affinity does not prevent pushing to cpu
3895 * 0 if chain is unpushable
3896 * -1 if chain is pushable but affinity blocks running on cpu.
3897 */
> 3898 int pushable_chain(struct rq *rq, struct task_struct *p, int cpu)
3899 {
3900 struct task_struct *exec_ctx;
3901
3902 lockdep_assert_rq_held(rq);
3903
3904 if (task_rq(p) != rq || !task_on_rq_queued(p))
3905 return 0;
3906
3907 exec_ctx = find_exec_ctx(rq, p);
3908 /*
3909 * Chain leads off the rq, we're free to push it anywhere.
3910 *
3911 * One wrinkle with relying on find_exec_ctx is that when the chain
3912 * leads to a task currently migrating to rq, we see the chain as
3913 * pushable & push everything prior to the migrating task. Even if
3914 * we checked explicitly for this case, we could still race with a
3915 * migration after the check.
3916 * This shouldn't permanently produce a bad state though, as proxy()
3917 * will send the chain back to rq and by that point the migration
3918 * should be complete & a proper push can occur.
3919 */
3920 if (!exec_ctx)
3921 return 1;
3922
3923 if (task_on_cpu(rq, exec_ctx) || exec_ctx->nr_cpus_allowed <= 1)
3924 return 0;
3925
3926 return cpumask_test_cpu(cpu, &exec_ctx->cpus_mask) ? 1 : -1;
3927 }
3928

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki