[PATCH 02/20] Do not sanity check order in the fast path

From: Mel Gorman
Date: Sun Feb 22 2009 - 18:16:40 EST


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.

Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
---
include/linux/gfp.h | 6 ------
mm/page_alloc.c | 2 ++
2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index dcf0ab8..8736047 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -181,9 +181,6 @@ __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();
@@ -197,9 +194,6 @@ 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 61051d5..c3842f8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1407,6 +1407,8 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,

classzone_idx = zone_idx(preferred_zone);

+ VM_BUG_ON(order >= MAX_ORDER);
+
zonelist_scan:
/*
* Scan zonelist, looking for a zone with enough free.
--
1.5.6.5

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