Index: sys/powerpc/ofw/ofw_machdep.c
===================================================================
--- sys/powerpc/ofw/ofw_machdep.c
+++ sys/powerpc/ofw/ofw_machdep.c
@@ -342,7 +342,19 @@
 
 		res = parse_ofw_memory(phandle, "reg", &memp[msz]);
 		msz += res/sizeof(struct mem_region);
-		if (OF_getproplen(phandle, "available") >= 0)
+
+		/* Order is important below. On POWER9 System, device-tree
+		 * might have both /linux,usable-memory and /reg properties
+		 * with different size values. For discovering memory slots, we
+		 * must use /linux-usable-memory otherwise we can grab NVlink
+		 * memories that contains len=0 on linux,usable-memory but >0 on
+		 * /reg property, even not being a standard memory region, which
+		 * is wrong and causes ghost memories to show up.
+		 */
+		if (OF_getproplen(phandle, "linux,usable-memory") >= 0)
+			res = parse_ofw_memory(phandle, "linux,usable-memory",
+			    &availp[asz]);
+		else if (OF_getproplen(phandle, "available") >= 0)
 			res = parse_ofw_memory(phandle, "available",
 			    &availp[asz]);
 		else