From: Quentin Perret <qperret@xxxxxxxxxx>
commit eaf5a92ebde5bca3bb2565616115bd6d579486cd upstream.
uclamp_fork() resets the uclamp values to their default when the
reset-on-fork flag is set. It also checks whether the task has a RT
policy, and sets its uclamp.min to 1024 accordingly. However, during
reset-on-fork, the task's policy is lowered to SCHED_NORMAL right after,
hence leading to an erroneous uclamp.min setting for the new task if it
was forked from RT.
Fix this by removing the unnecessary check on rt_task() in
uclamp_fork() as this doesn't make sense if the reset-on-fork flag is
set.
Fixes: 1a00d999971c ("sched/uclamp: Set default clamps for RT tasks")
Reported-by: Chitti Babu Theegala <ctheegal@xxxxxxxxxxxxxx>
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Patrick Bellasi <patrick.bellasi@xxxxxxxxxx>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Link: https://lkml.kernel.org/r/20200416085956.217587-1-qperret@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1239,13 +1239,8 @@ static void uclamp_fork(struct task_stru
return;
for_each_clamp_id(clamp_id) {
- unsigned int clamp_value = uclamp_none(clamp_id);
-
- /* By default, RT tasks always get 100% boost */
- if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
- clamp_value = uclamp_none(UCLAMP_MAX);
-
- uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false);
+ uclamp_se_set(&p->uclamp_req[clamp_id],
+ uclamp_none(clamp_id), false);
}
}
