+/*
+ * Fallback function if there was no memory available and no objects on a
+ * certain node and fall back is permitted. First we scan all the
+ * available nodelists for available objects. If that fails then we
+ * perform an allocation without specifying a node. This allows the page
+ * allocator to do its reclaim / fallback magic. We then insert the
+ * slab into the proper nodelist and then allocate from it.
+ */
+void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
+{
+ struct zonelist *zonelist = &NODE_DATA(slab_node(current->mempolicy))
+ ->node_zonelists[gfp_zone(flags)];
+ struct zone **z;
+ void *obj = NULL;
+ int nid;
+ gfp_t local_flags = (flags & GFP_LEVEL_MASK);
+
+retry:
+ /*
+ * Look through allowed nodes for objects available
+ * from existing per node queues.
+ */
+ for (z = zonelist->zones; *z && !obj; z++) {
+ nid = zone_to_nid(*z);
+
+ if (cpuset_zone_allowed_hardwall(*z, flags) &&
+ cache->nodelists[nid] &&
+ cache->nodelists[nid]->free_objects)
+ obj = ____cache_alloc_node(cache,
+ flags | GFP_THISNODE, nid);
+ }
+
+ if (!obj && !(flags & __GFP_NO_GROW)) {
+ /*
+ * This allocation will be performed within the constraints
+ * of the current cpuset / memory policy requirements.
+ * We may trigger various forms of reclaim on the allowed
+ * set and go into memory reserves if necessary.
+ */
+ if (local_flags & __GFP_WAIT)
+ local_irq_enable();
+ kmem_flagcheck(cache, flags);
+ obj = kmem_getpages(cache, flags, -1);
+ if (local_flags & __GFP_WAIT)
+ local_irq_disable();
+ if (obj) {
+ /*
+ * Insert into the appropriate per node queues
+ */
+ nid = page_to_nid(virt_to_page(obj));
+ if (cache_grow(cache, flags, nid, obj)) {
+ obj = ____cache_alloc_node(cache,
+ flags | GFP_THISNODE, nid);
+ if (!obj)
+ /*
+ * Another processor may allocate the
+ * objects in the slab since we are
+ * not holding any locks.
+ */
+ goto retry;
+ } else {
+ /* cache_grow already freed obj */
+ obj = NULL;
+ }
+ }
+ }
+ return obj;
+}
+