mm/page_alloc.c: remove duplicate call to trace_mm_page_free_direct

trace_mm_page_free_direct() is called in function __free_pages().  But it
is called again in free_hot_page() if order == 0 and produce duplicate
records in trace file for mm_page_free_direct event.  As below:

K-PID    CPU#    TIMESTAMP  FUNCTION
  gnome-terminal-1567  [000]  4415.246466: mm_page_free_direct: page=ffffea0003db9f40 pfn=1155800 order=0
  gnome-terminal-1567  [000]  4415.246468: mm_page_free_direct: page=ffffea0003db9f40 pfn=1155800 order=0
  gnome-terminal-1567  [000]  4415.246506: mm_page_alloc: page=ffffea0003db9f40 pfn=1155800 order=0 migratetype=0 gfp_flags=GFP_KERNEL
  gnome-terminal-1567  [000]  4415.255557: mm_page_free_direct: page=ffffea0003db9f40 pfn=1155800 order=0
  gnome-terminal-1567  [000]  4415.255557: mm_page_free_direct: page=ffffea0003db9f40 pfn=1155800 order=0

This patch removes the first call and adds a call to
trace_mm_page_free_direct() in __free_pages_ok().
Signed-off-by: Li Hong <lihong.hi@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Li Ming Chun <macli@brc.ubc.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -583,6 +583,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
 	int bad = 0;
 	int wasMlocked = __TestClearPageMlocked(page);
 
+	trace_mm_page_free_direct(page, order);
 	kmemcheck_free_shadow(page, order);
 
 	for (i = 0 ; i < (1 << order) ; ++i)
@@ -2008,7 +2009,6 @@ void __pagevec_free(struct pagevec *pvec)
 void __free_pages(struct page *page, unsigned int order)
 {
 	if (put_page_testzero(page)) {
-		trace_mm_page_free_direct(page, order);
 		if (order == 0)
 			free_hot_page(page);
 		else