From: "Steven Rostedt (VMware)" <rost...@goodmis.org>
The check for running in sched_move_task() has an unlikely() around it. That
is, it is unlikely that the task being moved is running. That use to be
true. But with a couple of recent updates, it is now likely that the task
will be running.
The first change came from ea86cb4b7621 ("sched/cgroup: Fix
cpu_cgroup_fork() handling") that moved around the use case of
sched_move_task() in do_fork() where the call is now done after the task is
woken (hence it is running).
The second change came from 8e5bfa8c1f84 ("sched/autogroup: Do not use
autogroup->tg in zombie threads") where sched_move_task() is called by the
exit path, by the task that is exiting. Hence it too is running.
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Vincent Guittot <vincent.guit...@linaro.org>
Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
kernel/sched/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c56fb57..669f23d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7989,14 +7989,14 @@ void sched_move_task(struct task_struct *tsk)
if (queued)
dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
- if (unlikely(running))
+ if (likely(running))
put_prev_task(rq, tsk);
sched_change_group(tsk, TASK_MOVE_GROUP);
if (queued)
enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
- if (unlikely(running))
+ if (likely(running))
set_curr_task(rq, tsk);
task_rq_unlock(rq, tsk, &rf);
--
2.9.3
