From: Mel Gorman <mel@csn.ul.ie>
Date: Tue, 16 Jun 2009 22:31:53 +0000 (-0700)
Subject: page allocator: do not sanity check order in the fast path
X-Git-Tag: upstream/snapshot3+hdmi~18577^2~154
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b3c466ce512923298ae8c0121d3e9f397a3f1210;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

page allocator: do not sanity check order in the fast path

No user of the allocator API should be passing in an order >= MAX_ORDER
but we check for it on each and every allocation.  Delete this check and
make it a VM_BUG_ON check further down the call path.

[akpm@linux-foundation.org: s/VM_BUG_ON/WARN_ON_ONCE/]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 549ec55..c2d3fe0 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -185,9 +185,6 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order,
 static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
 						unsigned int order)
 {
-	if (unlikely(order >= MAX_ORDER))
-		return NULL;
-
 	/* Unknown node is current node */
 	if (nid < 0)
 		nid = numa_node_id();
@@ -201,9 +198,6 @@ extern struct page *alloc_pages_current(gfp_t gfp_mask, unsigned order);
 static inline struct page *
 alloc_pages(gfp_t gfp_mask, unsigned int order)
 {
-	if (unlikely(order >= MAX_ORDER))
-		return NULL;
-
 	return alloc_pages_current(gfp_mask, order);
 }
 extern struct page *alloc_page_vma(gfp_t gfp_mask,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d58df90..bfbd95c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1401,6 +1401,9 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
 
 	classzone_idx = zone_idx(preferred_zone);
 
+	if (WARN_ON_ONCE(order >= MAX_ORDER))
+		return NULL;
+
 zonelist_scan:
 	/*
 	 * Scan zonelist, looking for a zone with enough free.