commit 7dc603c902 ("sched/fair: Fix PELT integrity for new tasks")
fixed two load tracking problems for new task, including detach on
unattached new task problem.
There still left another detach on unattached task problem for the task
which has been woken up by try_to_wake_up() and waiting for actually
being woken up by sched_ttwu_pending().
try_to_wake_up(p)
cpu = select_task_rq(p)
if (task_cpu(p) != cpu)
set_task_cpu(p, cpu)
migrate_task_rq_fair()
remove_entity_load_avg() --> unattached
se->avg.last_update_time = 0;
__set_task_cpu()
ttwu_queue(p, cpu)
ttwu_queue_wakelist()
__ttwu_queue_wakelist()
task_change_group_fair()
detach_task_cfs_rq()
detach_entity_cfs_rq()
detach_entity_load_avg() --> detach on unattached task
set_task_rq()
attach_task_cfs_rq()
attach_entity_cfs_rq()
attach_entity_load_avg()
The reason of this problem is similar, we should check in detach_entity_cfs_rq()
that se->avg.last_update_time != 0, before do detach_entity_load_avg().
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20220818124805.601-7-zhouchengming@bytedance.com
7e2edaf618