[tip: core/rcu] rcu: Shrink each possible cpu krcp

[tip-bot2 for Zqiang]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     70060b8770d34f83e9fa4c3526db013dd2773611
Gitweb:        https://git.kernel.org/tip/70060b8770d34f83e9fa4c3526db013dd2773611
Author:        Zqiang <qiang.zhang@xxxxxxxxxxxxx>
AuthorDate:    Fri, 14 Aug 2020 14:45:57 +08:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Thu, 03 Sep 2020 09:40:13 -07:00

rcu: Shrink each possible cpu krcp

CPUs can go offline shortly after kfree_call_rcu() has been invoked,
which can leave memory stranded until those CPUs come back online.
This commit therefore drains the kcrp of each CPU, not just the
ones that happen to be online.

Acked-by: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Zqiang <qiang.zhang@xxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 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 2323622..9245064 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3450,7 +3450,7 @@ 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);
@@ -3465,7 +3465,7 @@ 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);
 
@@ -3498,7 +3498,7 @@ 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);