diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index ed717dd..468626b 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -69,7 +69,7 @@
 static int depot_index;
 static int next_slab_inited;
 static size_t depot_offset;
-static DEFINE_SPINLOCK(depot_lock);
+static DEFINE_RAW_SPINLOCK(depot_lock);
 
 static bool init_stack_slab(void **prealloc)
 {
@@ -83,15 +83,19 @@
 		return true;
 	if (stack_slabs[depot_index] == NULL) {
 		stack_slabs[depot_index] = *prealloc;
+		*prealloc = NULL;
 	} else {
-		stack_slabs[depot_index + 1] = *prealloc;
+		/* If this is the last depot slab, do not touch the next one. */
+		if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) {
+			stack_slabs[depot_index + 1] = *prealloc;
+			*prealloc = NULL;
+		}
 		/*
 		 * This smp_store_release pairs with smp_load_acquire() from
 		 * |next_slab_inited| above and in stack_depot_save().
 		 */
 		smp_store_release(&next_slab_inited, 1);
 	}
-	*prealloc = NULL;
 	return true;
 }
 
@@ -265,7 +269,7 @@
 			prealloc = page_address(page);
 	}
 
-	spin_lock_irqsave(&depot_lock, flags);
+	raw_spin_lock_irqsave(&depot_lock, flags);
 
 	found = find_stack(*bucket, entries, nr_entries, hash);
 	if (!found) {
@@ -289,7 +293,7 @@
 		WARN_ON(!init_stack_slab(&prealloc));
 	}
 
-	spin_unlock_irqrestore(&depot_lock, flags);
+	raw_spin_unlock_irqrestore(&depot_lock, flags);
 exit:
 	if (prealloc) {
 		/* Nobody used this memory, ok to free it. */