diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 161d4fea7f5b..cf16728a94ed 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -1387,14 +1387,13 @@ dounmount(struct mount *mp, int flags, struct thread *td)
 		dounmount_cleanup(mp, coveredvp, 0);
 		return (EBUSY);
 	}
-	mp->mnt_kern_flag |= MNTK_UNMOUNT | MNTK_NOINSMNTQ;
+	mp->mnt_kern_flag |= MNTK_UNMOUNT;
 	if (flags & MNT_NONBUSY) {
 		MNT_IUNLOCK(mp);
 		error = vfs_check_usecounts(mp);
 		MNT_ILOCK(mp);
 		if (error != 0) {
-			dounmount_cleanup(mp, coveredvp, MNTK_UNMOUNT |
-			    MNTK_NOINSMNTQ);
+			dounmount_cleanup(mp, coveredvp, MNTK_UNMOUNT);
 			return (error);
 		}
 	}
@@ -1456,7 +1455,6 @@ dounmount(struct mount *mp, int flags, struct thread *td)
 	 */
 	if (error && error != ENXIO) {
 		MNT_ILOCK(mp);
-		mp->mnt_kern_flag &= ~MNTK_NOINSMNTQ;
 		if ((mp->mnt_flag & MNT_RDONLY) == 0) {
 			MNT_IUNLOCK(mp);
 			vfs_allocate_syncvnode(mp);
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 288a1ff905fa..d2012ee5f1b8 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1698,7 +1698,7 @@ insmntque1(struct vnode *vp, struct mount *mp,
 	 */
 	MNT_ILOCK(mp);
 	VI_LOCK(vp);
-	if (((mp->mnt_kern_flag & MNTK_NOINSMNTQ) != 0 &&
+	if (((mp->mnt_kern_flag & MNTK_UNMOUNT) != 0 &&
 	    ((mp->mnt_kern_flag & MNTK_UNMOUNTF) != 0 ||
 	    mp->mnt_nvnodelistsize == 0)) &&
 	    (vp->v_vflag & VV_FORCEINSMQ) == 0) {
@@ -3818,7 +3818,6 @@ DB_SHOW_COMMAND(mount, db_show_mount)
 	MNT_KERN_FLAG(MNTK_UNMOUNTF);
 	MNT_KERN_FLAG(MNTK_ASYNC);
 	MNT_KERN_FLAG(MNTK_SOFTDEP);
-	MNT_KERN_FLAG(MNTK_NOINSMNTQ);
 	MNT_KERN_FLAG(MNTK_DRAINING);
 	MNT_KERN_FLAG(MNTK_REFEXPIRE);
 	MNT_KERN_FLAG(MNTK_EXTENDED_SHARED);
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index 0bd6d9928074..2b7f988b7639 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -368,23 +368,20 @@ void          __mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *);
 /*
  * Internal filesystem control flags stored in mnt_kern_flag.
  *
- * MNTK_UNMOUNT locks the mount entry so that name lookup cannot proceed
- * past the mount point.  This keeps the subtree stable during mounts
- * and unmounts.
+ * MNTK_UNMOUNT locks the mount entry so that name lookup cannot
+ * proceed past the mount point.  This keeps the subtree stable during
+ * mounts and unmounts.  When non-forced unmount flushes all vnodes
+ * from the mp queue, the MNTK_UNMOUNT flag prevents insmntque() from
+ * queueing new vnodes.
  *
  * MNTK_UNMOUNTF permits filesystems to detect a forced unmount while
  * dounmount() is still waiting to lock the mountpoint. This allows
  * the filesystem to cancel operations that might otherwise deadlock
  * with the unmount attempt (used by NFS).
- *
- * MNTK_NOINSMNTQ is strict subset of MNTK_UNMOUNT. They are separated
- * to allow for failed unmount attempt to restore the syncer vnode for
- * the mount.
  */
 #define MNTK_UNMOUNTF	0x00000001	/* forced unmount in progress */
 #define MNTK_ASYNC	0x00000002	/* filtered async flag */
 #define MNTK_SOFTDEP	0x00000004	/* async disabled by softdep */
-#define MNTK_NOINSMNTQ	0x00000008	/* insmntque is not allowed */
 #define	MNTK_DRAINING	0x00000010	/* lock draining is happening */
 #define	MNTK_REFEXPIRE	0x00000020	/* refcount expiring is happening */
 #define MNTK_EXTENDED_SHARED	0x00000040 /* Allow shared locking for more ops */
diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
index 7a233536b316..aa7939c07b50 100644
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -2028,8 +2028,6 @@ retry_flush:
 		if (oldmnt->mnt_kern_flag & MNTK_UNMOUNT) {
 			retry = 0;
 			MNT_ILOCK(oldmnt);
-			KASSERT((oldmnt->mnt_kern_flag & MNTK_NOINSMNTQ) != 0,
-			    ("softdep_flushfiles: !MNTK_NOINSMNTQ"));
 			morework = oldmnt->mnt_nvnodelistsize > 0;
 #ifdef QUOTA
 			ump = VFSTOUFS(oldmnt);