Index: sys/kern/subr_busdma_bounce.c
===================================================================
--- sys/kern/subr_busdma_bounce.c
+++ sys/kern/subr_busdma_bounce.c
@@ -438,6 +438,7 @@
 	struct bus_dmamap *map, *nmap;
 
 	thread_lock(curthread);
+	sched_class(curthread, PRI_ITHD);
 	sched_prio(curthread, PI_SWI(SWI_BUSDMA));
 	thread_unlock(curthread);
 	for (;;) {