linux/kernel/sched
Rik van Riel fdaba61ef8 sched/fair: Ensure that the CFS parent is added after unthrottling
Ensure that a CFS parent will be in the list whenever one of its children is also
in the list.

A warning on rq->tmp_alone_branch != &rq->leaf_cfs_rq_list has been
reported while running LTP test cfs_bandwidth01.

Odin Ugedal found the root cause:

	$ tree /sys/fs/cgroup/ltp/ -d --charset=ascii
	/sys/fs/cgroup/ltp/
	|-- drain
	`-- test-6851
	    `-- level2
		|-- level3a
		|   |-- worker1
		|   `-- worker2
		`-- level3b
		    `-- worker3

Timeline (ish):
- worker3 gets throttled
- level3b is decayed, since it has no more load
- level2 get throttled
- worker3 get unthrottled
- level2 get unthrottled
  - worker3 is added to list
  - level3b is not added to list, since nr_running==0 and is decayed

 [ Vincent Guittot: Rebased and updated to fix for the reported warning. ]

Fixes: a7b359fc6a ("sched/fair: Correctly insert cfs_rq's to list on unthrottle")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Acked-by: Odin Ugedal <odin@uged.al>
Link: https://lore.kernel.org/r/20210621174330.11258-1-vincent.guittot@linaro.org
2021-06-22 14:06:57 +02:00
..
Makefile
autogroup.c
autogroup.h
clock.c
completion.c
core.c Revert "cpufreq: CPPC: Add support for frequency invariance" 2021-06-14 15:55:02 +02:00
cpuacct.c
cpudeadline.c
cpudeadline.h
cpufreq.c
cpufreq_schedutil.c
cpupri.c
cpupri.h
cputime.c
deadline.c
debug.c sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling 2021-06-03 15:47:23 +02:00
fair.c sched/fair: Ensure that the CFS parent is added after unthrottling 2021-06-22 14:06:57 +02:00
features.h
idle.c
isolation.c
loadavg.c
membarrier.c
pelt.c
pelt.h sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling 2021-06-03 15:47:23 +02:00
psi.c
rt.c
sched-pelt.h
sched.h
smp.h
stats.c
stats.h
stop_task.c
swait.c
topology.c
wait.c
wait_bit.c