[PATCH rcu 4/8] rcu/kvfree: Invoke debug_rcu_bhead_unqueue() after checking bnode->gp_snap

[Paul E. McKenney]

From: Zqiang <qiang1.zhang@xxxxxxxxx>

If kvfree_rcu_bulk() sees that the required grace period has failed to
elapse, it leaks the memory because readers might still be using it.
But in that case, the debug-objects subsystem still marks the relevant
structures as having been freed, even though they are instead being
leaked.

This commit fixes this mismatch by invoking debug_rcu_bhead_unqueue()
only when we are actually going to free the objects.

Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7452ba97ba34..426f1f3bb5f2 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2922,8 +2922,8 @@ kvfree_rcu_bulk(struct kfree_rcu_cpu *krcp,
 	unsigned long flags;
 	int i;
 
-	debug_rcu_bhead_unqueue(bnode);
 	if (!WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&bnode->gp_snap))) {
+		debug_rcu_bhead_unqueue(bnode);
 		rcu_lock_acquire(&rcu_callback_map);
 		if (idx == 0) { // kmalloc() / kfree().
 			trace_rcu_invoke_kfree_bulk_callback(
-- 
2.40.1