linux-brain/kernel/sched
Vincent Guittot 71c751cbb9 sched/fair: Make sure to update tg contrib for blocked load
commit 02da26ad5ed6ea8680e5d01f20661439611ed776 upstream.

During the update of fair blocked load (__update_blocked_fair()), we
update the contribution of the cfs in tg->load_avg if cfs_rq's pelt
has decayed.  Nevertheless, the pelt values of a cfs_rq could have
been recently updated while propagating the change of a child. In this
case, cfs_rq's pelt will not decayed because it has already been
updated and we don't update tg->load_avg.

__update_blocked_fair
  ...
  for_each_leaf_cfs_rq_safe: child cfs_rq
    update cfs_rq_load_avg() for child cfs_rq
    ...
    update_load_avg(cfs_rq_of(se), se, 0)
      ...
      update cfs_rq_load_avg() for parent cfs_rq
		-propagation of child's load makes parent cfs_rq->load_sum
		 becoming null
        -UPDATE_TG is not set so it doesn't update parent
		 cfs_rq->tg_load_avg_contrib
  ..
  for_each_leaf_cfs_rq_safe: parent cfs_rq
    update cfs_rq_load_avg() for parent cfs_rq
      - nothing to do because parent cfs_rq has already been updated
		recently so cfs_rq->tg_load_avg_contrib is not updated
    ...
    parent cfs_rq is decayed
      list_del_leaf_cfs_rq parent cfs_rq
	  - but it still contibutes to tg->load_avg

we must set UPDATE_TG flags when propagting pending load to the parent

Fixes: 039ae8bcf7 ("sched/fair: Fix O(nr_cgroups) in the load balancing path")
Reported-by: Odin Ugedal <odin@uged.al>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Odin Ugedal <odin@uged.al>
Link: https://lkml.kernel.org/r/20210527122916.27683-3-vincent.guittot@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-16 11:59:44 +02:00
..
autogroup.c sched/autogroup: Make autogroup_path() always available 2019-06-24 19:23:40 +02:00
autogroup.h sched/headers: Simplify and clean up header usage in the scheduler 2018-03-04 12:39:29 +01:00
clock.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
completion.c sched/Documentation: Update wake_up() & co. memory-barrier guarantees 2018-07-17 09:30:34 +02:00
core.c sched: Fix out-of-bound access in uclamp 2021-05-19 10:08:28 +02:00
cpuacct.c sched/headers: Simplify and clean up header usage in the scheduler 2018-03-04 12:39:29 +01:00
cpudeadline.c Linux 5.2-rc5 2019-06-17 12:12:27 +02:00
cpudeadline.h sched/headers: Simplify and clean up header usage in the scheduler 2018-03-04 12:39:29 +01:00
cpufreq_schedutil.c sched/uclamp: Protect uclamp fast path code with static key 2020-09-03 11:26:49 +02:00
cpufreq.c cpufreq: Avoid leaving stale IRQ work items during CPU offline 2019-12-31 16:46:06 +01:00
cpupri.c Linux 5.2-rc5 2019-06-17 12:12:27 +02:00
cpupri.h sched/headers: Simplify and clean up header usage in the scheduler 2018-03-04 12:39:29 +01:00
cputime.c sched/vtime: Fix guest/system mis-accounting on task switch 2019-10-09 12:38:03 +02:00
deadline.c sched/deadline: Fix sched_dl_global_validate() 2020-12-30 11:51:03 +01:00
debug.c sched/debug: Fix cgroup_path[] serialization 2021-05-14 09:44:26 +02:00
fair.c sched/fair: Make sure to update tg contrib for blocked load 2021-06-16 11:59:44 +02:00
features.h sched/fair: Replace source_load() & target_load() with weighted_cpuload() 2019-06-03 11:49:39 +02:00
idle.c rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 10:26:47 +01:00
isolation.c sched/isolation: Prefer housekeeping CPU in local node 2019-07-25 15:51:55 +02:00
loadavg.c timers/nohz: Update NOHZ load in remote tick 2020-03-05 16:43:36 +01:00
Makefile psi: pressure stall information for CPU, memory, and IO 2018-10-26 16:26:32 -07:00
membarrier.c sched/membarrier: fix missing local execution of ipi_sync_rq_state() 2021-03-17 17:03:57 +01:00
pelt.c sched/debug: Add new tracepoint to track PELT at se level 2019-06-24 19:23:42 +02:00
pelt.h sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity() 2019-06-24 19:23:39 +02:00
psi.c sched/psi: Fix OOB write when writing 0 bytes to PSI files 2020-02-28 17:22:21 +01:00
rt.c sched: Defend cfs and rt bandwidth quota against overflow 2020-06-22 09:31:07 +02:00
sched-pelt.h sched/fair: Fix "runnable_avg_yN_inv" not used warnings 2019-06-17 12:15:58 +02:00
sched.h sched/features: Fix hrtick reprogramming 2021-03-07 12:20:47 +01:00
stats.c proc: introduce proc_create_seq{,_data} 2018-05-16 07:23:35 +02:00
stats.h sched/stats: Fix unlikely() use of sched_info_on() 2019-07-25 15:51:55 +02:00
stop_task.c sched/core: Further clarify sched_class::set_next_task() 2020-01-26 10:01:03 +01:00
swait.c kernel/sched/: remove caller signal_pending branch predictions 2019-01-04 13:13:48 -08:00
topology.c sched: correct SD_flags returned by tl->sd_flags() 2020-08-19 08:15:54 +02:00
wait_bit.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
wait.c sched/wait: Deduplicate code with do-while 2019-06-24 19:23:40 +02:00