[PATCH 03/34] sched/core: Swap the order between sched_post_fork() and cgroup_post_fork()

[Tejun Heo]

The planned sched_ext cgroup sub-scheduler support needs the newly forked
task to be associated with its cgroup in its post_fork() hook. There is no
existing ordering requirement between the two now. Swap them and note the
new ordering requirement.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
 kernel/fork.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index e832da9d15a4..eb839b207cd4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2463,8 +2463,12 @@ __latent_entropy struct task_struct *copy_process(
 		fd_install(pidfd, pidfile);
 
 	proc_fork_connector(p);
-	sched_post_fork(p);
+	/*
+	 * sched_ext needs @p to be associated with its cgroup in its post_fork
+	 * hook. cgroup_post_fork() should come before sched_post_fork().
+	 */
 	cgroup_post_fork(p, args);
+	sched_post_fork(p);
 	perf_event_fork(p);
 
 	trace_task_newtask(p, clone_flags);
-- 
2.53.0