Unify memory policy layer functions for huge pages and slab.

We currently have multiple functions that determine policies for
certain specialized situations.

Generalize this into one single function that can cover all.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.18-rc1/mm/mempolicy.c
===================================================================
--- linux-2.6.18-rc1.orig/mm/mempolicy.c	2006-07-13 10:34:14.781057331 -0700
+++ linux-2.6.18-rc1/mm/mempolicy.c	2006-07-13 10:35:38.938928127 -0700
@@ -1125,33 +1125,6 @@ static unsigned interleave_nodes(struct 
 	return nid;
 }
 
-/*
- * Depending on the memory policy provide a node from which to allocate the
- * next slab entry.
- */
-unsigned slab_node(struct mempolicy *policy)
-{
-	switch (policy->policy) {
-	case MPOL_INTERLEAVE:
-		return interleave_nodes(policy);
-
-	case MPOL_BIND:
-		/*
-		 * Follow bind policy behavior and start allocation at the
-		 * first node.
-		 */
-		return policy->v.zonelist->zones[0]->zone_pgdat->node_id;
-
-	case MPOL_PREFERRED:
-		if (policy->v.preferred_node >= 0)
-			return policy->v.preferred_node;
-		/* Fall through */
-
-	default:
-		return numa_node_id();
-	}
-}
-
 /* Do static interleaving for a VMA with known offset. */
 static unsigned offset_il_node(struct mempolicy *pol,
 		struct vm_area_struct *vma, unsigned long off)
@@ -1183,21 +1156,23 @@ static inline unsigned interleave_nid(st
 		return interleave_nodes(pol);
 }
 
-#ifdef CONFIG_HUGETLBFS
-/* Return a zonelist suitable for a huge page allocation. */
-struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr)
+/* Return a zonelist proper for the vma, addresss and gfp mask. */
+struct zonelist *mpol_zonelist(gfp_t flags, int page_shift,
+			struct vm_area_struct *vma, unsigned long addr)
 {
 	struct mempolicy *pol = get_vma_policy(current, vma, addr);
 
+	if ((flags & __GFP_THISNODE) || in_interrupt())
+		pol = &default_policy;
+
 	if (pol->policy == MPOL_INTERLEAVE) {
 		unsigned nid;
 
-		nid = interleave_nid(pol, vma, addr, HPAGE_SHIFT);
-		return NODE_DATA(nid)->node_zonelists + gfp_zone(GFP_HIGHUSER);
+		nid = interleave_nid(pol, vma, addr, page_shift);
+		return NODE_DATA(nid)->node_zonelists + gfp_zone(flags);
 	}
-	return zonelist_policy(GFP_HIGHUSER, pol);
+	return zonelist_policy(flags, pol);
 }
-#endif
 
 /* Allocate a page in interleaved policy.
    Own path because it needs to do special accounting. */
Index: linux-2.6.18-rc1/mm/slab.c
===================================================================
--- linux-2.6.18-rc1.orig/mm/slab.c	2006-07-05 21:09:49.000000000 -0700
+++ linux-2.6.18-rc1/mm/slab.c	2006-07-13 10:34:21.984712486 -0700
@@ -3003,8 +3003,11 @@ static void *alternate_node_alloc(struct
 	nid_alloc = nid_here = numa_node_id();
 	if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
 		nid_alloc = cpuset_mem_spread_node();
-	else if (current->mempolicy)
-		nid_alloc = slab_node(current->mempolicy);
+	else if (current->mempolicy) {
+		struct zonelist *zonelist = mpol_zonelist(flags, 0, NULL, 0);
+
+		nid_alloc = zonelist->zones[0]->zone_pgdat->node_id;
+	}
 	if (nid_alloc != nid_here)
 		return __cache_alloc_node(cachep, flags, nid_alloc);
 	return NULL;
Index: linux-2.6.18-rc1/include/linux/mempolicy.h
===================================================================
--- linux-2.6.18-rc1.orig/include/linux/mempolicy.h	2006-07-05 21:09:49.000000000 -0700
+++ linux-2.6.18-rc1/include/linux/mempolicy.h	2006-07-13 10:34:21.986665490 -0700
@@ -158,9 +158,8 @@ extern void mpol_fix_fork_child_flag(str
 #endif
 
 extern struct mempolicy default_policy;
-extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
-		unsigned long addr);
-extern unsigned slab_node(struct mempolicy *policy);
+extern struct zonelist *mpol_zonelist(gfp_t flags, int page_shift,
+		struct vm_area_struct *vma, unsigned long addr);
 
 extern int policy_zone;
 
Index: linux-2.6.18-rc1/mm/hugetlb.c
===================================================================
--- linux-2.6.18-rc1.orig/mm/hugetlb.c	2006-07-05 21:09:49.000000000 -0700
+++ linux-2.6.18-rc1/mm/hugetlb.c	2006-07-13 10:34:21.987641992 -0700
@@ -68,7 +68,8 @@ static struct page *dequeue_huge_page(st
 {
 	int nid = numa_node_id();
 	struct page *page = NULL;
-	struct zonelist *zonelist = huge_zonelist(vma, address);
+	struct zonelist *zonelist =
+		mpol_zonelist(GFP_HIGHUSER, HPAGE_SHIFT, vma, address);
 	struct zone **z;
 
 	for (z = zonelist->zones; *z; z++) {