[PATCH] restore CHECK_EMERGENCY_SYNC. Again.

Put the CHECK_EMERGENCY_SYNC back into the kupdate function.  I seem to
keep removing it.

mm/page-writeback.c

@@ -19,7 +19,7 @@
 #include <linux/pagemap.h>
 #include <linux/writeback.h>
 #include <linux/init.h>
-//#include <linux/sysrq.h>
+#include <linux/sysrq.h>
 #include <linux/backing-dev.h>
 #include <linux/mpage.h>
 
@@ -171,6 +171,8 @@ static void background_writeout(unsigned long _min_pages)
 	long min_pages = _min_pages;
 	int nr_to_write;
 
+	CHECK_EMERGENCY_SYNC
+
 	do {
 		struct page_state ps;