static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
{
	struct list_head *freeable = arg;
	struct dentry	*dentry = container_of(item, struct dentry, d_lru);

	/*
	 * we are inverting the lru lock/dentry->d_lock here,
	 * so use a trylock. If we fail to get the lock, just skip
	 * it
	 */
	if (!spin_trylock(&dentry->d_lock))
		return LRU_SKIP;

	d_lru_shrink_move(lru, dentry, freeable);
	spin_unlock(&dentry->d_lock);

	return LRU_REMOVED;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.