t = old_root_dir + sizeof(root_dir) - 1;
if (umount2(t, MNT_DETACH) < 0)
/* At this point it's too late to turn anything back,
t = old_root_dir + sizeof(root_dir) - 1;
if (umount2(t, MNT_DETACH) < 0)
/* At this point it's too late to turn anything back,