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-rw-r--r--kernel/sched/ext/idle.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/sched/ext/idle.c b/kernel/sched/ext/idle.c
index d2973fb3af6d..aa9fb6de0ad6 100644
--- a/kernel/sched/ext/idle.c
+++ b/kernel/sched/ext/idle.c
@@ -1142,10 +1142,17 @@ __bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64
#ifdef CONFIG_EXT_SUB_SCHED
/*
* Disallow if any sub-scheds are attached. There is no way to tell
- * which scheduler called us, just error out @p's scheduler.
+ * which scheduler called us, so error out @p's scheduler -- read it
+ * under RCU as @p's locks aren't necessarily held here. @p may be a
+ * task past sched_ext_dead() or an idle task, in which case its
+ * scheduler can't be determined and there is nothing obviously wrong
+ * to report; just refuse the call.
*/
if (unlikely(!list_empty(&sch->children))) {
- scx_error(scx_task_sched(p), "__scx_bpf_select_cpu_and() must be used");
+ struct scx_sched *tsch = scx_task_sched_rcu(p);
+
+ if (tsch)
+ scx_error(tsch, "__scx_bpf_select_cpu_and() must be used");
return -EINVAL;
}
#endif