Index: sys/kern/kern_shutdown.c
===================================================================
--- sys/kern/kern_shutdown.c
+++ sys/kern/kern_shutdown.c
@@ -132,6 +132,11 @@
 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RWTUN,
 	&sync_on_panic, 0, "Do a sync before rebooting from a panic");
 
+static int stop_scheduler_on_dump = 1;
+SYSCTL_INT(_kern, OID_AUTO, stop_scheduler_on_dump, CTLFLAG_RW,
+    &stop_scheduler_on_dump, 0,
+    "Stop the scheduler if a dump is requested on reboot");
+
 static SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0,
     "Shutdown environment");
 
@@ -332,6 +337,32 @@
 	return (error);
 }
 
+static void
+stop_scheduler(bool stop_cpus, int *bootopt)
+{
+#ifdef SMP
+	cpuset_t other_cpus;
+#endif
+
+	spinlock_enter();
+
+#ifdef SMP
+	if (stop_cpus) {
+		other_cpus = all_cpus;
+		CPU_CLR(PCPU_GET(cpuid), &other_cpus);
+		stop_cpus_hard(other_cpus);
+	}
+
+	/*
+	 * Ensure that the scheduler is stopped while panicking, even if panic
+	 * has been entered from kdb.
+	 */
+	curthread->td_stopsched = 1;
+#endif
+	if (!sync_on_panic)
+		*bootopt |= RB_NOSYNC;
+}
+
 /*
  * Shutdown the system cleanly to prepare for reboot, halt, or power off.
  */
@@ -382,8 +413,19 @@
 	 */
 	EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
 
-	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) 
+	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) {
+		/*
+		 * Dump code assumes that all other CPUs have stopped, and thus handles
+		 * disk interrupts manually. This assumption must be enforced, as
+		 * otherwise the real interrupt handler may race with the dumper.
+		 * Dumping with a running scheduler may also produce inconsistent
+		 * dumps.
+		 */
+		if (!SCHEDULER_STOPPED() && stop_scheduler_on_dump)
+			stop_scheduler(true, &howto);
+
 		doadump(TRUE);
+	}
 
 	/* Now that we're going to really halt the system... */
 	EVENTHANDLER_INVOKE(shutdown_final, howto);
@@ -713,35 +755,18 @@
 void
 vpanic(const char *fmt, va_list ap)
 {
-#ifdef SMP
-	cpuset_t other_cpus;
-#endif
 	struct thread *td = curthread;
 	int bootopt, newpanic;
 	static char buf[256];
 
-	spinlock_enter();
-
-#ifdef SMP
-	/*
-	 * stop_cpus_hard(other_cpus) should prevent multiple CPUs from
-	 * concurrently entering panic.  Only the winner will proceed
-	 * further.
-	 */
-	if (panicstr == NULL && !kdb_active) {
-		other_cpus = all_cpus;
-		CPU_CLR(PCPU_GET(cpuid), &other_cpus);
-		stop_cpus_hard(other_cpus);
-	}
+	bootopt = RB_AUTOBOOT;
 
 	/*
-	 * Ensure that the scheduler is stopped while panicking, even if panic
-	 * has been entered from kdb.
+	 * stop_scheduler should prevent multiple CPUs from concurrently
+	 * entering panic.  Only the winner will proceed further.
 	 */
-	td->td_stopsched = 1;
-#endif
+	stop_scheduler(panicstr == NULL && !kdb_active, &bootopt);
 
-	bootopt = RB_AUTOBOOT;
 	newpanic = 0;
 	if (panicstr)
 		bootopt |= RB_NOSYNC;
@@ -774,8 +799,6 @@
 	/*thread_lock(td); */
 	td->td_flags |= TDF_INPANIC;
 	/* thread_unlock(td); */
-	if (!sync_on_panic)
-		bootopt |= RB_NOSYNC;
 	kern_reboot(bootopt);
 }