From: Uladzislau Rezki (Sony) <urezki@gmail.com>
Date: Thu, 15 Apr 2021 17:19:58 +0000 (+0200)
Subject: kvfree_rcu: Add a bulk-list check when a scheduler is run
X-Git-Tag: v5.14-rc1~78^2^4~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d434c00fa3ac476ca6295b8310d097dd71984624;p=thirdparty%2Flinux.git

kvfree_rcu: Add a bulk-list check when a scheduler is run

The rcu_scheduler_active flag is set to RCU_SCHEDULER_RUNNING once the
scheduler is up and running.  That signal is used in order to check
and queue a "monitor work" to reclaim freed objects (if there are any)
during early boot.  This flag is used by kvfree_rcu() to determine when
work can safely be queued, at which point memory passed to earlier
invocations of kvfree_rcu() can be processed.

However, only "krcp->head" is checked for objects that need to be
released, and there are now two more, namely, "krcp->bkvhead[0]" and
"krcp->bkvhead[1]".  Therefore, check these two additional channels.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 676a49ab5b2b4..e86f32d6b8f94 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3739,7 +3739,8 @@ void __init kfree_rcu_scheduler_running(void)
 		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
 
 		raw_spin_lock_irqsave(&krcp->lock, flags);
-		if (!krcp->head || krcp->monitor_todo) {
+		if ((!krcp->bkvhead[0] && !krcp->bkvhead[1] && !krcp->head) ||
+				krcp->monitor_todo) {
 			raw_spin_unlock_irqrestore(&krcp->lock, flags);
 			continue;
 		}