diff -Naur mdadm-4.2/Assemble.c mdadm-4.2-fix/Assemble.c
--- mdadm-4.2/Assemble.c	2025-10-25 11:46:59.647889913 +0800
+++ mdadm-4.2-fix/Assemble.c	2025-10-25 11:37:18.437758159 +0800
@@ -1337,10 +1337,8 @@
 	return 1;
 }
 
-int Assemble(struct supertype *st, char *mddev,
-	     struct mddev_ident *ident,
-	     struct mddev_dev *devlist,
-	     struct context *c)
+int Assemble(char *mddev, struct mddev_ident *ident,
+	     struct mddev_dev *devlist, struct context *c)
 {
 	/*
 	 * The task of Assemble is to find a collection of
@@ -1427,6 +1425,7 @@
 	char chosen_name[1024];
 	struct map_ent *map = NULL;
 	struct map_ent *mp;
+	struct supertype *st = NULL;
 
 	/*
 	 * If any subdevs are listed, then any that don't
@@ -1447,6 +1446,15 @@
 		return 1;
 	}
 
+	if (c->metadata) {
+		for (i = 0; !st && superlist[i]; i++)
+			st = superlist[i]->match_metadata_desc(c->metadata);
+		if (!st) {
+			pr_err("unrecognised metadata identifier: %s\n", c->metadata);
+			return -EINVAL;
+		}
+	}
+
 	if (devlist == NULL)
 		devlist = conf_get_devs();
 	else if (mddev)
@@ -1468,11 +1476,15 @@
 		st->ignore_hw_compat = 1;
 	num_devs = select_devices(devlist, ident, &st, &content, c,
 				  inargv, auto_assem);
-	if (num_devs < 0)
-		return 1;
+	if (num_devs < 0) {
+		rv = 1;
+		goto free_st;
+	}
 
-	if (!st || !st->sb || !content)
-		return 2;
+	if (!st || !st->sb || !content) {
+		rv = 2;
+		goto free_st;
+	}
 
 	/* We have a full set of devices - we now need to find the
 	 * array device.
@@ -1603,11 +1615,10 @@
 
 	if (content != &info) {
 		/* This is a member of a container.  Try starting the array. */
-		int err;
-		err = assemble_container_content(st, mdfd, content, c,
+		rv = assemble_container_content(st, mdfd, content, c,
 						 chosen_name, NULL);
 		close(mdfd);
-		return err;
+		goto free_st;
 	}
 
 	/* Ok, no bad inconsistancy, we can try updating etc */
@@ -1961,9 +1972,19 @@
 	/* '2' means 'OK, but not started yet' */
 	if (rv == -1) {
 		free(devices);
-		return 1;
+		rv = 1;
+		goto free_st;
 	}
-	return rv == 2 ? 0 : rv;
+
+	if (rv == 2)
+		rv = 0;
+free_st:
+	if (st) {
+		st->ss->free_super(st);
+		free(st);
+	}
+
+	return rv;
 }
 
 int assemble_container_content(struct supertype *st, int mdfd,
diff -Naur mdadm-4.2/mdadm.c mdadm-4.2-fix/mdadm.c
--- mdadm-4.2/mdadm.c	2025-10-25 11:46:59.527825090 +0800
+++ mdadm-4.2-fix/mdadm.c	2025-10-25 11:42:17.331226086 +0800
@@ -71,6 +71,7 @@
 	 */
 	struct context c = {
 		.require_homehost = 1,
+		.metadata = NULL,
 	};
 	struct shape s = {
 		.journaldisks	= 0,
@@ -402,6 +403,7 @@
 				pr_err("unrecognised metadata identifier: %s\n", optarg);
 				exit(2);
 			}
+			c.metadata = optarg;
 			continue;
 
 		case O(MANAGE,'W'):
@@ -1427,10 +1429,10 @@
 			} else {
 				if (array_ident->autof == 0)
 					array_ident->autof = c.autof;
-				rv |= Assemble(ss, ident.devname, array_ident, NULL, &c);
+				rv |= Assemble(ident.devname, array_ident, NULL, &c);
 			}
 		} else if (!c.scan)
-			rv = Assemble(ss, ident.devname, &ident, devlist->next, &c);
+			rv = Assemble(ident.devname, &ident, devlist->next, &c);
 		else if (devs_found > 0) {
 			if (c.update && devs_found > 1) {
 				pr_err("can only update a single array at a time\n");
@@ -1450,8 +1452,7 @@
 				}
 				if (array_ident->autof == 0)
 					array_ident->autof = c.autof;
-				rv |= Assemble(ss, dv->devname, array_ident,
-					       NULL, &c);
+				rv |= Assemble(dv->devname, array_ident, NULL, &c);
 			}
 		} else {
 			if (c.update) {
@@ -1736,8 +1737,7 @@
 			if (a->devname && is_devname_ignore(a->devname) == true)
 				continue;
 
-			r = Assemble(ss, a->devname,
-				     a, NULL, c);
+			r = Assemble(a->devname, a, NULL, c);
 			if (r == 0) {
 				a->assembled = 1;
 				successes++;
@@ -1759,9 +1759,7 @@
 			struct mddev_dev *devlist = conf_get_devs();
 			acnt = 0;
 			do {
-				rv2 = Assemble(ss, NULL,
-					       ident,
-					       devlist, c);
+				rv2 = Assemble(NULL, ident, devlist, c);
 				if (rv2 == 0) {
 					cnt++;
 					acnt++;
diff -Naur mdadm-4.2/mdadm.h mdadm-4.2-fix/mdadm.h
--- mdadm-4.2/mdadm.h	2025-10-25 11:46:59.716186280 +0800
+++ mdadm-4.2-fix/mdadm.h	2025-10-25 11:43:13.999603357 +0800
@@ -662,6 +662,7 @@
 	char	*action;
 	int	nodes;
 	char	*homecluster;
+	char	*metadata;
 };
 
 struct shape {
@@ -1541,10 +1542,8 @@
 extern int Grow_continue_command(char *devname, int fd,
 				 char *backup_file, int verbose);
 
-extern int Assemble(struct supertype *st, char *mddev,
-		    struct mddev_ident *ident,
-		    struct mddev_dev *devlist,
-		    struct context *c);
+extern int Assemble(char *mddev, struct mddev_ident *ident,
+			struct mddev_dev *devlist, struct context *c);
 
 extern int Build(struct mddev_ident *ident, struct mddev_dev *devlist, struct shape *s,
 		 struct context *c);