rcu: Add support for debug_objects debugging for kfree_rcu() (e99637be) · Commits · 戴 / test

This commit applies RCU's debug_objects debugging to the new batched kfree_rcu() implementations. The object is queued at the kfree_rcu() call and dequeued during reclaim. Tested that enabling CONFIG_DEBUG_OBJECTS_RCU_HEAD successfully detects double kfree_rcu() calls. Signed-off-by:

Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Fix IRQ per kbuild test robot <lkp@intel.com> feedback. ] Signed-off-by:

Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/tree.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -2749,6 +2749,7 @@ static void kfree_rcu_work(struct work_struct *work)
		for (; head; head = next) {
		next = head->next;
		// Potentially optimize with kfree_bulk in future.
		debug_rcu_head_unqueue(head);
		__rcu_reclaim(rcu_state.name, head);
		cond_resched_tasks_rcu_qs();
		}
		@@ -2855,6 +2856,12 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
		spin_lock(&krcp->lock);

		// Queue the object but don't yet schedule the batch.
		if (debug_rcu_head_queue(head)) {
		// Probable double kfree_rcu(), just leak.
		WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
		__func__, head);
		goto unlock_return;
		}
		head->func = func;
		head->next = krcp->head;
		krcp->head = head;
		@@ -2866,6 +2873,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
		schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
		}

		unlock_return:
		if (krcp->initialized)
		spin_unlock(&krcp->lock);
		local_irq_restore(flags);

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