kernel_optimize_test/kernel/sched
Quentin Perret e6778e1b22 sched: Fix UCLAMP_FLAG_IDLE setting
[ Upstream commit ca4984a7dd863f3e1c0df775ae3e744bff24c303 ]

The UCLAMP_FLAG_IDLE flag is set on a runqueue when dequeueing the last
uclamp active task (that is, when buckets.tasks reaches 0 for all
buckets) to maintain the last uclamp.max and prevent blocked util from
suddenly becoming visible.

However, there is an asymmetry in how the flag is set and cleared which
can lead to having the flag set whilst there are active tasks on the rq.
Specifically, the flag is cleared in the uclamp_rq_inc() path, which is
called at enqueue time, but set in uclamp_rq_dec_id() which is called
both when dequeueing a task _and_ in the update_uclamp_active() path. As
a result, when both uclamp_rq_{dec,ind}_id() are called from
update_uclamp_active(), the flag ends up being set but not cleared,
hence leaving the runqueue in a broken state.

Fix this by clearing the flag in update_uclamp_active() as well.

Fixes: e496187da7 ("sched/uclamp: Enforce last task's UCLAMP_MAX")
Reported-by: Rick Yiu <rickyiu@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Qais Yousef <qais.yousef@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20210805102154.590709-2-qperret@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-09-15 09:50:28 +02:00
..
autogroup.c
autogroup.h
clock.c
completion.c completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all() 2020-03-23 18:40:25 +01:00
core.c sched: Fix UCLAMP_FLAG_IDLE setting 2021-09-15 09:50:28 +02:00
cpuacct.c sched/cpuacct: Fix charge cpuacct.usage_sys 2020-05-19 20:34:14 +02:00
cpudeadline.c sched/deadline: Implement fallback mechanism for !fit case 2020-06-15 14:10:05 +02:00
cpudeadline.h
cpufreq_schedutil.c cpufreq: Introduce governor flags 2020-11-10 18:31:17 +01:00
cpufreq.c
cpupri.c sched/rt: cpupri_find: Trigger a full search as fallback 2020-03-20 13:06:20 +01:00
cpupri.h sched/rt: Optimize cpupri_find() on non-heterogenous systems 2020-03-06 12:57:27 +01:00
cputime.c sched/cputime: Improve cputime_adjust() 2020-06-15 14:10:00 +02:00
deadline.c sched/deadline: Fix missing clock update in migrate_task_rq_dl() 2021-09-15 09:50:24 +02:00
debug.c sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling 2021-06-16 12:01:46 +02:00
fair.c sched/numa: Fix is_core_idle() 2021-09-15 09:50:28 +02:00
features.h sched,fair: Alternative sched_slice() 2021-05-11 14:47:31 +02:00
idle.c rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 11:38:35 +01:00
isolation.c isolcpus: Affine unbound kernel threads to housekeeping cpus 2020-06-15 14:10:03 +02:00
loadavg.c sched: nohz: stop passing around unused "ticks" parameter. 2020-07-22 10:22:04 +02:00
Makefile
membarrier.c sched/membarrier: fix missing local execution of ipi_sync_rq_state() 2021-03-17 17:06:35 +01:00
pelt.c sched: Add a tracepoint to track rq->nr_running 2020-07-08 11:39:02 +02:00
pelt.h sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling 2021-06-16 12:01:46 +02:00
psi.c psi: Fix race between psi_trigger_create/destroy 2021-07-14 16:56:10 +02:00
rt.c sched/rt: Fix RT utilization tracking during policy change 2021-07-14 16:56:09 +02:00
sched-pelt.h
sched.h sched/deadline: Fix reset_on_fork reporting of DL tasks 2021-09-15 09:50:24 +02:00
smp.h sched/headers: Split out open-coded prototypes into kernel/sched/smp.h 2020-05-28 11:03:20 +02:00
stats.c
stats.h psi: Move PF_MEMSTALL out of task->flags 2020-03-20 13:06:19 +01:00
stop_task.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
swait.c sched/swait: Prepare usage in completions 2020-03-21 16:00:23 +01:00
topology.c Scheduler changes for v5.10: 2020-10-12 12:56:01 -07:00
wait_bit.c
wait.c rq-qos: fix missed wake-ups in rq_qos_throttle try two 2021-07-19 09:45:00 +02:00