From: Zqiang <qiang1.zhang@intel.com>
Date: Thu, 24 Mar 2022 11:15:15 +0000 (+0800)
Subject: rcu: Check for successful spawn of ->boost_kthread_task
X-Git-Tag: v5.19-rc1~252^2~1^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=88ca472f80604c070526eb58b977ea0a9c3c2e1f;p=thirdparty%2Fkernel%2Fstable.git

rcu: Check for successful spawn of ->boost_kthread_task

For the spawning of the priority-boost kthreads can fail, improbable
though this might seem.  This commit therefore refrains from attemoting
to initiate RCU priority boosting when The ->boost_kthread_task pointer
is NULL.

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 176639c6215fb..5c23aceecd62d 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1125,7 +1125,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
 	__releases(rnp->lock)
 {
 	raw_lockdep_assert_held_rcu_node(rnp);
-	if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
+	if (!rnp->boost_kthread_task ||
+	    (!rcu_preempt_blocked_readers_cgp(rnp) && !rnp->exp_tasks)) {
 		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 		return;
 	}