linux-kernel - [PATCH 18/46] sched/core: Swap the order between sched_post_fork() and cgroup_post

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Message-ID: <20250920005931.2753828-19-tj@kernel.org>
Date: Fri, 19 Sep 2025 14:58:41 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
	arighi@...dia.com,
	multics69@...il.com
Cc: linux-kernel@...r.kernel.org,
	sched-ext@...ts.linux.dev,
	memxor@...il.com,
	bpf@...r.kernel.org,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 18/46] sched/core: Swap the order between sched_post_fork() and cgroup_post_fork()

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@...nel.org>
---
 kernel/fork.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index af673856499d..6e5a1397d2e6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2415,8 +2415,12 @@ __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);
-- 
2.51.0