Index: grub2-2.04/grub-core/osdep/linux/getroot.c
===================================================================
--- grub2-2.04.orig/grub-core/osdep/linux/getroot.c
+++ grub2-2.04/grub-core/osdep/linux/getroot.c
@@ -135,10 +135,18 @@ struct mountinfo_entry
   char fstype[ESCAPED_PATH_MAX + 1], device[ESCAPED_PATH_MAX + 1];
 };
 
+/* GET_DISK_INFO nr_disks (total count) does not map to disk.number,
+   which is an internal kernel index. Instead, do what mdadm does
+   and keep scanning until we find enough valid disks. The limit is
+   copied from there, which notes that it is sufficiently high given
+   that the on-disk metadata for v1.x can only support 1920.  */
+#define MD_MAX_DISKS       4096
+
 static char **
 grub_util_raid_getmembers (const char *name, int bootable)
 {
   int fd, ret, i, j;
+  int remaining;
   char **devicelist;
   mdu_version_t version;
   mdu_array_info_t info;
@@ -170,12 +178,17 @@ grub_util_raid_getmembers (const char *n
 
   devicelist = xcalloc (info.nr_disks + 1, sizeof (char *));
 
-  for (i = 0, j = 0; i < info.nr_disks; i++)
+  remaining = info.nr_disks;
+  for (i = 0, j = 0; i < MD_MAX_DISKS && remaining > 0; i++)
     {
       disk.number = i;
       ret = ioctl (fd, GET_DISK_INFO, &disk);
       if (ret != 0)
 	grub_util_error (_("ioctl GET_DISK_INFO error: %s"), strerror (errno));
+      /* Skip empty disk slot. */
+      if (disk.major == 0 && disk.minor == 0)
+	continue;
+      remaining--;
 
       if (disk.state & (1 << MD_DISK_REMOVED))
 	continue;