Index: src/sys/kern/kern_lock.c
@@ -58,6 +58,7 @@
     (LK_ADAPTIVE | LK_CANRECURSE | LK_NOSHARE));
 CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
     ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS)));
+CTASSERT((LK_DISOWNED & LO_CLASSFLAGS) == LK_DISOWNED);
 
 #define	SQ_EXCLUSIVE_QUEUE	0
 #define	SQ_SHARED_QUEUE		1
@@ -127,7 +128,7 @@
 	((f) & LK_SLEEPFAIL) == 0)
 
 #define	lockmgr_disowned(lk)						\
-	(((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC)
+	(((lk)->lock_object.lo_flags & LK_DISOWNED) == LK_DISOWNED)
 
 #define	lockmgr_xlocked(lk)						\
 	(((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread)
@@ -446,7 +447,7 @@
 			 * changes.
 			 */
 			if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
-			    LK_HOLDER(x) != LK_KERNPROC) {
+			    !lockmgr_disowned(lk)) {
 				owner = (struct thread *)LK_HOLDER(x);
 				if (LOCK_LOG_TEST(&lk->lock_object, 0))
 					CTR3(KTR_LOCK,
@@ -517,7 +518,7 @@
 			 * again.
 			 */
 			if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
-			    LK_HOLDER(x) != LK_KERNPROC) {
+			    !lockmgr_disowned(lk)) {
 				owner = (struct thread *)LK_HOLDER(x);
 				if (TD_IS_RUNNING(owner)) {
 					sleepq_release(&lk->lock_object);
@@ -659,7 +660,7 @@
 			 */
 			x = lk->lk_lock;
 			if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
-			    LK_HOLDER(x) != LK_KERNPROC) {
+			    !lockmgr_disowned(lk)) {
 				owner = (struct thread *)LK_HOLDER(x);
 				if (LOCK_LOG_TEST(&lk->lock_object, 0))
 					CTR3(KTR_LOCK,
@@ -733,7 +734,7 @@
 			 * again.
 			 */
 			if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
-			    LK_HOLDER(x) != LK_KERNPROC) {
+			    !lockmgr_disowned(lk)) {
 				owner = (struct thread *)LK_HOLDER(x);
 				if (TD_IS_RUNNING(owner)) {
 					sleepq_release(&lk->lock_object);
@@ -832,15 +833,17 @@
 		x = lk->lk_lock;
 
 		if ((x & LK_SHARE) == 0) {
+			int anon = 0;
 
 			/*
 			 * As first option, treact the lock as if it has not
 			 * any waiter.
 			 * Fix-up the tid var if the lock has been disowned.
 			 */
-			if (LK_HOLDER(x) == LK_KERNPROC)
-				tid = LK_KERNPROC;
-			else {
+			if (lockmgr_disowned(lk)) {
+				tid = LK_HOLDER(lk->lk_lock);
+				anon++;
+			} else {
 				WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE,
 				    file, line);
 				TD_LOCKS_DEC(curthread);
@@ -858,7 +861,9 @@
 				lk->lk_recurse--;
 				break;
 			}
-			if (tid != LK_KERNPROC)
+			if (anon)
+				lk->lock_object.lo_flags &= ~LK_DISOWNED;
+			else
 				lock_profile_release_lock(&lk->lock_object);
 
 			if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid,
@@ -1033,33 +1038,21 @@
 void
 _lockmgr_disown(struct lock *lk, const char *file, int line)
 {
-	uintptr_t tid, x;
+	uintptr_t tid;
 
 	tid = (uintptr_t)curthread;
 	_lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
 
 	/*
-	 * If the owner is already LK_KERNPROC just skip the whole operation.
+	 * If the lock has already been disowned just skip the whole operation.
 	 */
-	if (LK_HOLDER(lk->lk_lock) != tid)
+	if (lockmgr_disowned(lk))
 		return;
 	lock_profile_release_lock(&lk->lock_object);
 	LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
 	WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
 	TD_LOCKS_DEC(curthread);
-
-	/*
-	 * In order to preserve waiters flags, just spin.
-	 */
-	for (;;) {
-		x = lk->lk_lock;
-		MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
-		x &= LK_ALL_WAITERS;
-		if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
-		    LK_KERNPROC | x))
-			return;
-		cpu_spinwait();
-	}
+	lk->lock_object.lo_flags |= LK_DISOWNED;
 }
 
 void
@@ -1102,7 +1095,7 @@
 	v = LK_HOLDER(x);
 
 	if ((x & LK_SHARE) == 0) {
-		if (v == (uintptr_t)curthread || v == LK_KERNPROC)
+		if (v == (uintptr_t)curthread || lockmgr_disowned(lk))
 			ret = LK_EXCLUSIVE;
 		else
 			ret = LK_EXCLOTHER;
@@ -1225,12 +1218,11 @@
 		db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock));
 	else {
 		td = lockmgr_xholder(lk);
-		if (td == (struct thread *)LK_KERNPROC)
-			db_printf("XLOCK: LK_KERNPROC\n");
-		else
-			db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
-			    td->td_tid, td->td_proc->p_pid,
-			    td->td_proc->p_comm);
+		db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
+		    td->td_tid, td->td_proc->p_pid,
+		    td->td_proc->p_comm);
+		if (lockmgr_disowned(lk))
+			db_printf(" disowned\n");
 		if (lockmgr_recursed(lk))
 			db_printf(" recursed: %d\n", lk->lk_recurse);
 	}
Index: src/sys/sys/lockmgr.h
@@ -38,6 +38,7 @@
 #include <sys/stack.h>
 #endif
 
+/* Stored in the lock_object lock field */
 #define	LK_SHARE			0x01
 #define	LK_SHARED_WAITERS		0x02
 #define	LK_EXCLUSIVE_WAITERS		0x04
@@ -53,7 +54,9 @@
 #define	LK_SHARERS_LOCK(x)		((x) << LK_SHARERS_SHIFT | LK_SHARE)
 #define	LK_ONE_SHARER			(1 << LK_SHARERS_SHIFT)
 #define	LK_UNLOCKED			LK_SHARERS_LOCK(0)
-#define	LK_KERNPROC			((uintptr_t)(-1) & ~LK_FLAGMASK)
+
+/* Stored in the lock_object class flags */
+#define LK_DISOWNED			0x10
 
 struct lock {
 	struct lock_object	lock_object;