[PATCH rcu 09/11] rcu: Check for successful spawn of ->boost_kthread_task

From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
	rostedt@goodmis.org, Zqiang <qiang1.zhang@intel.com>,
	"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 09/11] rcu: Check for successful spawn of ->boost_kthread_task
Date: Mon, 18 Apr 2022 15:53:57 -0700	[thread overview]
Message-ID: <20220418225359.3945217-9-paulmck@kernel.org> (raw)
In-Reply-To: <20220418225345.GA3945110@paulmck-ThinkPad-P17-Gen-1>

From: Zqiang <qiang1.zhang@intel.com>

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>
---
 kernel/rcu/tree_plugin.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 176639c6215f..5c23aceecd62 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;
 	}
-- 
2.31.1.189.g2e36527f23

