diff --git a/sys/kern/kern_linker.c b/sys/kern/kern_linker.c
--- a/sys/kern/kern_linker.c
+++ b/sys/kern/kern_linker.c
@@ -106,6 +106,7 @@
 linker_file_t linker_kernel_file;
 
 static struct sx kld_sx;	/* kernel linker lock */
+static bool kld_busy;
 
 /*
  * Load counter used by clients to determine if a linker file has been
@@ -1050,6 +1051,40 @@
 	    M_WAITOK));
 }
 
+int
+linker_set_busy(bool unlock, bool interruptible)
+{
+	int error;
+
+	sx_xlock(&kld_sx);
+	while (kld_busy) {
+		error = sx_sleep(&kld_busy, &kld_sx, interruptible ? PCATCH :
+		    0, "kldser1", 0);
+		if (error != 0) {
+			if (unlock)
+				sx_xunlock(&kld_sx);
+			return (error);
+		}
+	}
+	kld_busy = true;
+	if (unlock)
+		sx_xunlock(&kld_sx);
+	return (0);
+}
+
+void
+linker_set_unbusy(bool locked)
+{
+	if (locked)
+		sx_assert(&kld_sx, SA_XLOCKED);
+	else
+		sx_xlock(&kld_sx);
+	MPASS(kld_busy);
+	kld_busy = false;
+	wakeup(&kld_busy);
+	sx_xunlock(&kld_sx);
+}
+
 /*
  * Syscalls.
  */
@@ -1066,12 +1101,6 @@
 	if ((error = priv_check(td, PRIV_KLD_LOAD)) != 0)
 		return (error);
 
-	/*
-	 * It is possible that kldloaded module will attach a new ifnet,
-	 * so vnet context must be set when this ocurs.
-	 */
-	CURVNET_SET(TD_TO_VNET(td));
-
 	/*
 	 * If file does not contain a qualified name or any dot in it
 	 * (kldname.ko, or kldname.ver.ko) treat it as an interface
@@ -1085,19 +1114,27 @@
 		modname = file;
 	}
 
-	sx_xlock(&kld_sx);
-	error = linker_load_module(kldname, modname, NULL, NULL, &lf);
-	if (error) {
+	error = linker_set_busy(false, true);
+	if (error != 0) {
 		sx_xunlock(&kld_sx);
-		goto done;
+		return (error);
 	}
-	lf->userrefs++;
-	if (fileid != NULL)
-		*fileid = lf->id;
-	sx_xunlock(&kld_sx);
 
-done:
+	/*
+	 * It is possible that kldloaded module will attach a new ifnet,
+	 * so vnet context must be set when this ocurs.
+	 */
+	CURVNET_SET(TD_TO_VNET(td));
+
+	error = linker_load_module(kldname, modname, NULL, NULL, &lf);
 	CURVNET_RESTORE();
+
+	if (error == 0) {
+		lf->userrefs++;
+		if (fileid != NULL)
+			*fileid = lf->id;
+	}
+	linker_set_unbusy(true);
 	return (error);
 }
 
@@ -1132,8 +1169,13 @@
 	if ((error = priv_check(td, PRIV_KLD_UNLOAD)) != 0)
 		return (error);
 
+	error = linker_set_busy(false, true);
+	if (error != 0) {
+		sx_xunlock(&kld_sx);
+		return (error);
+	}
+
 	CURVNET_SET(TD_TO_VNET(td));
-	sx_xlock(&kld_sx);
 	lf = linker_find_file_by_id(fileid);
 	if (lf) {
 		KLD_DPF(FILE, ("kldunload: lf->userrefs=%d\n", lf->userrefs));
@@ -1153,9 +1195,8 @@
 		}
 	} else
 		error = ENOENT;
-	sx_xunlock(&kld_sx);
-
 	CURVNET_RESTORE();
+	linker_set_unbusy(true);
 	return (error);
 }
 
diff --git a/sys/kern/subr_firmware.c b/sys/kern/subr_firmware.c
--- a/sys/kern/subr_firmware.c
+++ b/sys/kern/subr_firmware.c
@@ -251,6 +251,8 @@
 	linker_file_t result;
 	int error;
 
+	error = linker_set_busy(true, false);
+	MPASS(error == 0);
 	error = linker_reference_module(fwli->imagename, NULL, &result);
 	if (error != 0) {
 		if (bootverbose || (fwli->flags & FIRMWARE_GET_NOWARN) == 0)
@@ -275,6 +277,7 @@
 done:
 	wakeup_one(arg);
 	mtx_unlock(&firmware_mtx);
+	linker_set_unbusy(false);
 }
 
 /*
diff --git a/sys/sys/linker.h b/sys/sys/linker.h
--- a/sys/sys/linker.h
+++ b/sys/sys/linker.h
@@ -196,6 +196,10 @@
 /* HWPMC helper */
 void *linker_hwpmc_list_objects(void);
 
+/* kldload/kldunload syscalls blocking */
+int linker_set_busy(bool unlock, bool interruptible);
+void linker_set_unbusy(bool locked);
+
 #endif	/* _KERNEL */
 
 /*