Index: sys/kern/kern_lock.c
===================================================================
--- sys/kern/kern_lock.c
+++ sys/kern/kern_lock.c
@@ -1003,10 +1003,34 @@
 			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_SHARERS_LOCK(1) | x))
-				break;
-			cpu_spinwait();
+			if ((x & LK_EXCLUSIVE_WAITERS) ||
+			    !(x & LK_SHARED_WAITERS)) {
+				if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
+				    LK_SHARERS_LOCK(1) | x))
+					break;
+				cpu_spinwait();
+				continue;
+			}
+
+			sleepq_lock(&lk->lock_object);
+			x = lk->lk_lock;
+			x &= LK_ALL_WAITERS;
+
+			if ((x & LK_EXCLUSIVE_WAITERS) ||
+			    !(x & LK_SHARED_WAITERS) ||
+			    !atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
+			    LK_SHARERS_LOCK(1) | (x & ~LK_SHARED_WAITERS))) {
+				sleepq_release(&lk->lock_object);
+				continue;
+			}
+			LOCK_LOG2(lk,
+			    "%s: %p waking up threads on the shared queue",
+			    __func__, lk);
+			lk->lk_exslpfail = 0;
+			wakeup_swapper |= sleepq_broadcast(&lk->lock_object,
+			    SLEEPQ_LK, 0, SQ_SHARED_QUEUE);
+			sleepq_release(&lk->lock_object);
+			break;
 		}
 		break;
 	case LK_RELEASE: