linux-kernel - [PATCH RFC 14/14] rcu: Remove checking of per-cpu blocked list against the node list

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Message-Id: <20260103002343.6599-15-joelagnelf@nvidia.com>
Date: Fri,  2 Jan 2026 19:23:43 -0500
From: Joel Fernandes <joelagnelf@...dia.com>
To: linux-kernel@...r.kernel.org
Cc: "Paul E . McKenney" <paulmck@...nel.org>,
	Frederic Weisbecker <frederic@...nel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Joel Fernandes <joelagnelf@...dia.com>,
	Josh Triplett <josh@...htriplett.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Zqiang <qiang.zhang@...ux.dev>,
	Uladzislau Rezki <urezki@...il.com>,
	joel@...lfernandes.org,
	rcu@...r.kernel.org
Subject: [PATCH RFC 14/14] rcu: Remove checking of per-cpu blocked list against the node list

Now that the verification check consistently is verified, remove it. It
is still kept in the patch series for illustration/testing purposes.

Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
---
 kernel/rcu/tree.c | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 468388970c98..9d9d7c5ff3fc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1900,26 +1900,6 @@ static noinline_for_stack bool rcu_gp_init(void)
 		arch_spin_lock(&rcu_state.ofl_lock);
 		raw_spin_lock_rcu_node(rnp);
 		rcu_promote_blocked_tasks(rnp);
-#ifdef CONFIG_RCU_PER_CPU_BLOCKED_LISTS
-		/*
-		 * Verify rdp lists consistent with rnp list. Since the unlock
-		 * path removes from rdp before rnp, we can have tasks that are
-		 * on rnp but not on rdp (in the middle of being removed).
-		 * Therefore rnp_count >= rdp_total is the expected invariant.
-		 */
-		rnp_count = 0;
-		rdp_total = 0;
-		list_for_each_entry(t_verify, &rnp->blkd_tasks, rcu_node_entry)
-			rnp_count++;
-		for (cpu_verify = rnp->grplo; cpu_verify <= rnp->grphi; cpu_verify++) {
-			rdp_cpu = per_cpu_ptr(&rcu_data, cpu_verify);
-			raw_spin_lock(&rdp_cpu->blkd_lock);
-			list_for_each_entry(t_rdp, &rdp_cpu->blkd_list, rcu_rdp_entry)
-				rdp_total++;
-			raw_spin_unlock(&rdp_cpu->blkd_lock);
-		}
-		WARN_ON_ONCE(rnp_count < rdp_total);
-#endif
 		if (rnp->qsmaskinit == rnp->qsmaskinitnext &&
 		    !rnp->wait_blkd_tasks) {
 			/* Nothing to do on this leaf rcu_node structure. */
-- 
2.34.1