page allocator: do not check NUMA node ID when the caller knows the node is valid

Callers of alloc_pages_node() can optionally specify -1 as a node to mean
"allocate from the current node".  However, a number of the callers in
fast paths know for a fact their node is valid.  To avoid a comparison and
branch, this patch adds alloc_pages_exact_node() that only checks the nid
with VM_BUG_ON().  Callers that know their node is valid are then
converted.

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>
Acked-by: Paul Mundt <lethal@linux-sh.org>	[for the SLOB NUMA bits]
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>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 18e3164de09a..bb3254c95cd2 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1707,7 +1707,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
         if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                 flags |= __GFP_RECLAIMABLE;
 
-        page = alloc_pages_node(nodeid, flags, cachep->gfporder);
+        page = alloc_pages_exact_node(nodeid, flags, cachep->gfporder);
         if (!page)
                 return NULL;
 
@@ -3261,7 +3261,7 @@ retry:
                 if (local_flags & __GFP_WAIT)
                         local_irq_enable();
                 kmem_flagcheck(cache, flags);
-                obj = kmem_getpages(cache, local_flags, -1);
+                obj = kmem_getpages(cache, local_flags, numa_node_id());
                 if (local_flags & __GFP_WAIT)
                         local_irq_disable();
                 if (obj) {