page allocator: check only once if the zonelist is suitable for the allocation

gormanm · torvalds · commit 7f82af9742a9 · 2009-06-16T19:47:32.000-07:00
It is possible with __GFP_THISNODE that no zones are suitable.  This patch
makes sure the check is only made once.

Signed-off-by: Mel Gorman &lt;mel@csn.ul.ie&gt;
Reviewed-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Reviewed-by: KOSAKI Motohiro &lt;kosaki.motohiro@jp.fujitsu.com&gt;
Reviewed-by: Pekka Enberg &lt;penberg@cs.helsinki.fi&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Nick Piggin &lt;nickpiggin@yahoo.com.au&gt;
Cc: Dave Hansen &lt;dave@linux.vnet.ibm.com&gt;
Cc: Lee Schermerhorn &lt;Lee.Schermerhorn@hp.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
@@ -1483,9 +1483,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	if (should_fail_alloc_page(gfp_mask, order))
 		return NULL;
 
-restart:
-	z = zonelist->_zonerefs;  /* the list of zones suitable for gfp_mask */
-
+	/* the list of zones suitable for gfp_mask */
+	z = zonelist->_zonerefs;
 	if (unlikely(!z->zone)) {
 		/*
 		 * Happens if we have an empty zonelist as a result of
@@ -1494,6 +1493,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 		return NULL;
 	}
 
+restart:
 	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
 			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET);
 	if (page)
