linux-kernel - [PATCH] rcu: shrink each possible cpu krcp

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Date:   Fri, 14 Aug 2020 14:45:57 +0800
From:   <qiang.zhang@...driver.com>
To:     <paulmck@...nel.org>, <josh@...htriplett.org>,
        <rostedt@...dmis.org>, <mathieu.desnoyers@...icios.com>,
        <jiangshanlai@...il.com>, <joel@...lfernandes.org>
CC:     <rcu@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] rcu: shrink each possible cpu krcp

From: Zqiang <qiang.zhang@...driver.com>

Due to cpu hotplug. some cpu may be offline after call "kfree_call_rcu"
func, if the shrinker is triggered at this time, we should drain each
possible cpu "krcp".

Signed-off-by: Zqiang <qiang.zhang@...driver.com>
---
 kernel/rcu/tree.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8ce77d9ac716..619ccbb3fe4b 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3443,7 +3443,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
 	unsigned long count = 0;
 
 	/* Snapshot count of all CPUs */
-	for_each_online_cpu(cpu) {
+	for_each_possible_cpu(cpu) {
 		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
 
 		count += READ_ONCE(krcp->count);
@@ -3458,7 +3458,7 @@ kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 	int cpu, freed = 0;
 	unsigned long flags;
 
-	for_each_online_cpu(cpu) {
+	for_each_possible_cpu(cpu) {
 		int count;
 		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
 
@@ -3491,7 +3491,7 @@ void __init kfree_rcu_scheduler_running(void)
 	int cpu;
 	unsigned long flags;
 
-	for_each_online_cpu(cpu) {
+	for_each_possible_cpu(cpu) {
 		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
 
 		raw_spin_lock_irqsave(&krcp->lock, flags);
-- 
2.17.1