mm: filter based on a nodemask as well as a gfp_mask

The MPOL_BIND policy creates a zonelist that is used for allocations
controlled by that mempolicy.  As the per-node zonelist is already being
filtered based on a zone id, this patch adds a version of __alloc_pages() that
takes a nodemask for further filtering.  This eliminates the need for
MPOL_BIND to create a custom zonelist.

A positive benefit of this is that allocations using MPOL_BIND now use the
local node's distance-ordered zonelist instead of a custom node-id-ordered
zonelist.  I.e., pages will be allocated from the closest allowed node with
available memory.

[Lee.Schermerhorn@hp.com: Mempolicy: update stale documentation and comments]
[Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask]
[Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask rework]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 73 insertions, 111 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 90193a2a915b..acb5ee3587c3 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -163,42 +163,25 @@ static int mpol_check_policy(int mode, nodemask_t *nodes)
         return 0;
 }
 
-/* Generate a custom zonelist for the BIND policy. */
-static struct zonelist *bind_zonelist(nodemask_t *nodes)
+/* Check that the nodemask contains at least one populated zone */
+static int is_valid_nodemask(nodemask_t *nodemask)
 {
-        struct zonelist *zl;
-        int num, max, nd;
-        enum zone_type k;
+        int nd, k;
 
-        max = 1 + MAX_NR_ZONES * nodes_weight(*nodes);
-        max++;                  /* space for zlcache_ptr (see mmzone.h) */
-        zl = kmalloc(sizeof(struct zone *) * max, GFP_KERNEL);
-        if (!zl)
-                return ERR_PTR(-ENOMEM);
-        zl->zlcache_ptr = NULL;
-        num = 0;
-        /* First put in the highest zones from all nodes, then all the next 
-           lower zones etc. Avoid empty zones because the memory allocator
-           doesn't like them. If you implement node hot removal you
-           have to fix that. */
-        k = MAX_NR_ZONES - 1;
-        while (1) {
-                for_each_node_mask(nd, *nodes) { 
-                        struct zone *z = &NODE_DATA(nd)->node_zones[k];
-                        if (z->present_pages > 0) 
-                                zoneref_set_zone(z, &zl->_zonerefs[num++]);
+        /* Check that there is something useful in this mask */
+        k = policy_zone;
+
+        for_each_node_mask(nd, *nodemask) {
+                struct zone *z;
+
+                for (k = 0; k <= policy_zone; k++) {
+                        z = &NODE_DATA(nd)->node_zones[k];
+                        if (z->present_pages > 0)
+                                return 1;
                 }
-                if (k == 0)
-                        break;
-                k--;
-        }
-        if (num == 0) {
-                kfree(zl);
-                return ERR_PTR(-EINVAL);
         }
-        zl->_zonerefs[num].zone = NULL;
-        zl->_zonerefs[num].zone_idx = 0;
-        return zl;
+
+        return 0;
 }
 
 /* Create a new policy */
@@ -229,12 +212,11 @@ static struct mempolicy *mpol_new(int mode, nodemask_t *nodes)
                         policy->v.preferred_node = -1;
                 break;
         case MPOL_BIND:
-                policy->v.zonelist = bind_zonelist(nodes);
-                if (IS_ERR(policy->v.zonelist)) {
-                        void *error_code = policy->v.zonelist;
+                if (!is_valid_nodemask(nodes)) {
                         kmem_cache_free(policy_cache, policy);
-                        return error_code;
+                        return ERR_PTR(-EINVAL);
                 }
+                policy->v.nodes = *nodes;
                 break;
         }
         policy->policy = mode;
@@ -500,19 +482,12 @@ static long do_set_mempolicy(int mode, nodemask_t *nodes)
 /* Fill a zone bitmap for a policy */
 static void get_zonemask(struct mempolicy *p, nodemask_t *nodes)
 {
-        int i;
-
         nodes_clear(*nodes);
         switch (p->policy) {
-        case MPOL_BIND:
-                for (i = 0; p->v.zonelist->_zonerefs[i].zone; i++) {
-                        struct zoneref *zref;
-                        zref = &p->v.zonelist->_zonerefs[i];
-                        node_set(zonelist_node_idx(zref), *nodes);
-                }
-                break;
         case MPOL_DEFAULT:
                 break;
+        case MPOL_BIND:
+                /* Fall through */
         case MPOL_INTERLEAVE:
                 *nodes = p->v.nodes;
                 break;
@@ -1160,6 +1135,18 @@ static struct mempolicy * get_vma_policy(struct task_struct *task,
         return pol;
 }
 
+/* Return a nodemask representing a mempolicy */
+static nodemask_t *nodemask_policy(gfp_t gfp, struct mempolicy *policy)
+{
+        /* Lower zones don't get a nodemask applied for MPOL_BIND */
+        if (unlikely(policy->policy == MPOL_BIND) &&
+                        gfp_zone(gfp) >= policy_zone &&
+                        cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
+                return &policy->v.nodes;
+
+        return NULL;
+}
+
 /* Return a zonelist representing a mempolicy */
 static struct zonelist *zonelist_policy(gfp_t gfp, struct mempolicy *policy)
 {
@@ -1172,12 +1159,17 @@ static struct zonelist *zonelist_policy(gfp_t gfp, struct mempolicy *policy)
                         nd = numa_node_id();
                 break;
         case MPOL_BIND:
-                /* Lower zones don't get a policy applied */
-                /* Careful: current->mems_allowed might have moved */
-                if (gfp_zone(gfp) >= policy_zone)
-                        if (cpuset_zonelist_valid_mems_allowed(policy->v.zonelist))
-                                return policy->v.zonelist;
-                /*FALL THROUGH*/
+                /*
+                 * Normally, MPOL_BIND allocations node-local are node-local
+                 * within the allowed nodemask. However, if __GFP_THISNODE is
+                 * set and the current node is part of the mask, we use the
+                 * the zonelist for the first node in the mask instead.
+                 */
+                nd = numa_node_id();
+                if (unlikely(gfp & __GFP_THISNODE) &&
+                                unlikely(!node_isset(nd, policy->v.nodes)))
+                        nd = first_node(policy->v.nodes);
+                break;
         case MPOL_INTERLEAVE: /* should not happen */
         case MPOL_DEFAULT:
                 nd = numa_node_id();
@@ -1220,7 +1212,14 @@ unsigned slab_node(struct mempolicy *policy)
                  * Follow bind policy behavior and start allocation at the
                  * first node.
                  */
-                return zonelist_node_idx(policy->v.zonelist->_zonerefs);
+                struct zonelist *zonelist;
+                struct zone *zone;
+                enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
+                zonelist = &NODE_DATA(numa_node_id())->node_zonelists[0];
+                (void)first_zones_zonelist(zonelist, highest_zoneidx,
+                                                        &policy->v.nodes,
+                                                        &zone);
+                return zone->node;
         }
 
         case MPOL_PREFERRED:
@@ -1278,25 +1277,31 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
  * @vma = virtual memory area whose policy is sought
  * @addr = address in @vma for shared policy lookup and interleave policy
  * @gfp_flags = for requested zone
- * @mpol = pointer to mempolicy pointer for reference counted 'BIND policy
+ * @mpol = pointer to mempolicy pointer for reference counted mempolicy
+ * @nodemask = pointer to nodemask pointer for MPOL_BIND nodemask
  *
  * Returns a zonelist suitable for a huge page allocation.
- * If the effective policy is 'BIND, returns pointer to policy's zonelist.
+ * If the effective policy is 'BIND, returns pointer to local node's zonelist,
+ * and a pointer to the mempolicy's @nodemask for filtering the zonelist.
  * If it is also a policy for which get_vma_policy() returns an extra
- * reference, we must hold that reference until after allocation.
+ * reference, we must hold that reference until after the allocation.
  * In that case, return policy via @mpol so hugetlb allocation can drop
- * the reference.  For non-'BIND referenced policies, we can/do drop the
+ * the reference. For non-'BIND referenced policies, we can/do drop the
  * reference here, so the caller doesn't need to know about the special case
  * for default and current task policy.
  */
 struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
-                                gfp_t gfp_flags, struct mempolicy **mpol)
+                                gfp_t gfp_flags, struct mempolicy **mpol,
+                                nodemask_t **nodemask)
 {
         struct mempolicy *pol = get_vma_policy(current, vma, addr);
         struct zonelist *zl;
 
         *mpol = NULL;           /* probably no unref needed */
-        if (pol->policy == MPOL_INTERLEAVE) {
+        *nodemask = NULL;       /* assume !MPOL_BIND */
+        if (pol->policy == MPOL_BIND) {
+                        *nodemask = &pol->v.nodes;
+        } else if (pol->policy == MPOL_INTERLEAVE) {
                 unsigned nid;
 
                 nid = interleave_nid(pol, vma, addr, HPAGE_SHIFT);
@@ -1376,14 +1381,15 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
                 /*
                  * slow path: ref counted policy -- shared or vma
                  */
-                struct page *page =  __alloc_pages(gfp, 0, zl);
+                struct page *page =  __alloc_pages_nodemask(gfp, 0,
+                                                zl, nodemask_policy(gfp, pol));
                 __mpol_free(pol);
                 return page;
         }
         /*
          * fast path:  default or task policy
          */
-        return __alloc_pages(gfp, 0, zl);
+        return __alloc_pages_nodemask(gfp, 0, zl, nodemask_policy(gfp, pol));
 }
 
 /**
@@ -1415,7 +1421,8 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
                 pol = &default_policy;
         if (pol->policy == MPOL_INTERLEAVE)
                 return alloc_page_interleave(gfp, order, interleave_nodes(pol));
-        return __alloc_pages(gfp, order, zonelist_policy(gfp, pol));
+        return __alloc_pages_nodemask(gfp, order,
+                        zonelist_policy(gfp, pol), nodemask_policy(gfp, pol));
 }
 EXPORT_SYMBOL(alloc_pages_current);
 
@@ -1440,14 +1447,6 @@ struct mempolicy *__mpol_copy(struct mempolicy *old)
         }
         *new = *old;
         atomic_set(&new->refcnt, 1);
-        if (new->policy == MPOL_BIND) {
-                int sz = ksize(old->v.zonelist);
-                new->v.zonelist = kmemdup(old->v.zonelist, sz, GFP_KERNEL);
-                if (!new->v.zonelist) {
-                        kmem_cache_free(policy_cache, new);
-                        return ERR_PTR(-ENOMEM);
-                }
-        }
         return new;
 }
 
@@ -1461,21 +1460,12 @@ int __mpol_equal(struct mempolicy *a, struct mempolicy *b)
         switch (a->policy) {
         case MPOL_DEFAULT:
                 return 1;
+        case MPOL_BIND:
+                /* Fall through */
         case MPOL_INTERLEAVE:
                 return nodes_equal(a->v.nodes, b->v.nodes);
         case MPOL_PREFERRED:
                 return a->v.preferred_node == b->v.preferred_node;
-        case MPOL_BIND: {
-                int i;
-                for (i = 0; a->v.zonelist->_zonerefs[i].zone; i++) {
-                        struct zone *za, *zb;
-                        za = zonelist_zone(&a->v.zonelist->_zonerefs[i]);
-                        zb = zonelist_zone(&b->v.zonelist->_zonerefs[i]);
-                        if (za != zb)
-                                return 0;
-                }
-                return b->v.zonelist->_zonerefs[i].zone == NULL;
-        }
         default:
                 BUG();
                 return 0;
@@ -1487,8 +1477,6 @@ void __mpol_free(struct mempolicy *p)
 {
         if (!atomic_dec_and_test(&p->refcnt))
                 return;
-        if (p->policy == MPOL_BIND)
-                kfree(p->v.zonelist);
         p->policy = MPOL_DEFAULT;
         kmem_cache_free(policy_cache, p);
 }
@@ -1779,6 +1767,8 @@ static void mpol_rebind_policy(struct mempolicy *pol,
         switch (pol->policy) {
         case MPOL_DEFAULT:
                 break;
+        case MPOL_BIND:
+                /* Fall through */
         case MPOL_INTERLEAVE:
                 nodes_remap(tmp, pol->v.nodes, *mpolmask, *newmask);
                 pol->v.nodes = tmp;
@@ -1791,32 +1781,6 @@ static void mpol_rebind_policy(struct mempolicy *pol,
                                                 *mpolmask, *newmask);
                 *mpolmask = *newmask;
                 break;
-        case MPOL_BIND: {
-                nodemask_t nodes;
-                struct zoneref *z;
-                struct zonelist *zonelist;
-
-                nodes_clear(nodes);
-                for (z = pol->v.zonelist->_zonerefs; z->zone; z++)
-                        node_set(zonelist_node_idx(z), nodes);
-                nodes_remap(tmp, nodes, *mpolmask, *newmask);
-                nodes = tmp;
-
-                zonelist = bind_zonelist(&nodes);
-
-                /* If no mem, then zonelist is NULL and we keep old zonelist.
-                 * If that old zonelist has no remaining mems_allowed nodes,
-                 * then zonelist_policy() will "FALL THROUGH" to MPOL_DEFAULT.
-                 */
-
-                if (!IS_ERR(zonelist)) {
-                        /* Good - got mem - substitute new zonelist */
-                        kfree(pol->v.zonelist);
-                        pol->v.zonelist = zonelist;
-                }
-                *mpolmask = *newmask;
-                break;
-        }
         default:
                 BUG();
                 break;
@@ -1879,9 +1843,7 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
                 break;
 
         case MPOL_BIND:
-                get_zonemask(pol, &nodes);
-                break;
-
+                /* Fall through */
         case MPOL_INTERLEAVE:
                 nodes = pol->v.nodes;
                 break;