sched: Inherit task cookie on fork()

Note that sched_core_fork() is called from under tasklist_lock, and
not from sched_fork() earlier. This avoids a few races later.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Don Hiatt <dhiatt@digitalocean.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.980003687@infradead.org

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c
index 8d0869a9eb8c..dcbbeaefaaa3 100644
--- a/kernel/sched/core_sched.c
+++ b/kernel/sched/core_sched.c
@@ -103,6 +103,12 @@ static unsigned long sched_core_clone_cookie(struct task_struct *p)
 	return cookie;
 }
 
+void sched_core_fork(struct task_struct *p)
+{
+	RB_CLEAR_NODE(&p->core_node);
+	p->core_cookie = sched_core_clone_cookie(current);
+}
+
 void sched_core_free(struct task_struct *p)
 {
 	sched_core_put_cookie(p->core_cookie);