diff --git a/lib/idr.c b/lib/idr.c
index 6098336..7767abe 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -30,6 +30,7 @@
 #include <linux/idr.h>
 #include <linux/spinlock.h>
 #include <linux/percpu.h>
+#include <linux/mm.h>
 
 #define MAX_IDR_SHIFT		(sizeof(int) * 8 - 1)
 #define MAX_IDR_BIT		(1U << MAX_IDR_SHIFT)
@@ -194,6 +195,9 @@ static int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
 	while (idp->id_free_cnt < MAX_IDR_FREE) {
 		struct idr_layer *new;
 		new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
+		pr_err("HERE: %s:%d allocated %p from idr_layer_cache\n", __FILE__, __LINE__, new);
+		pr_err("idr_layer_cache: %p, slab_cache: %p\n", idr_layer_cache, virt_to_page(new)->slab_cache);
+		BUG_ON(virt_to_page(new)->slab_cache != idr_layer_cache);
 		if (new == NULL)
 			return (0);
 		move_to_free_list(idp, new);