If we get a stray interrupt, return after logging it. In the extremely

rare case of a stray interrupt to an unregistered source (such as a stray
interrupt from the 8259As when using APIC), this could result in a page
fault when it tried to walk the list of interrupt handlers to execute
INTR_FAST handlers.  This bug was introduced with the intr_event changes,
so it's not present in 5.x or 6.x.

Submitted by:	Mark Tinguely tinguely at casselton dot net

sys/amd64/amd64/intr_machdep.c

@@ -190,6 +190,7 @@ intr_execute_handlers(struct intsrc *isrc, struct intrframe *iframe)
 			log(LOG_CRIT,
 			    "too many stray irq %d's: not logging anymore\n",
 			    vector);
+		return;
 	}
 
 	/*

sys/i386/i386/intr_machdep.c

@@ -190,6 +190,7 @@ intr_execute_handlers(struct intsrc *isrc, struct intrframe *iframe)
 			log(LOG_CRIT,
 			    "too many stray irq %d's: not logging anymore\n",
 			    vector);
+		return;
 	}
 
 	/*