1 files changed, 31 insertions, 5 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index be211a582930..a4cfcdc00455 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -415,12 +415,14 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
          * This means the page allocator ignores this zone.
          * So, zonelist must be updated after online.
          */
+        mutex_lock(&zonelists_mutex);
         if (!populated_zone(zone))
                 need_zonelists_rebuild = 1;
 
         ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
                 online_pages_range);
         if (ret) {
+                mutex_unlock(&zonelists_mutex);
                 printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
                         nr_pages, pfn);
                 memory_notify(MEM_CANCEL_ONLINE, &arg);
@@ -429,8 +431,12 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 
         zone->present_pages += onlined_pages;
         zone->zone_pgdat->node_present_pages += onlined_pages;
+        if (need_zonelists_rebuild)
+                build_all_zonelists(zone);
+        else
+                zone_pcp_update(zone);
 
-        zone_pcp_update(zone);
+        mutex_unlock(&zonelists_mutex);
         setup_per_zone_wmarks();
         calculate_zone_inactive_ratio(zone);
         if (onlined_pages) {
@@ -438,10 +444,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
                 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
         }
 
-        if (need_zonelists_rebuild)
-                build_all_zonelists();
-        else
-                vm_total_pages = nr_free_pagecache_pages();
+        vm_total_pages = nr_free_pagecache_pages();
 
         writeback_set_ratelimit();
 
@@ -482,6 +485,29 @@ static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
 }
 
 
+/*
+ * called by cpu_up() to online a node without onlined memory.
+ */
+int mem_online_node(int nid)
+{
+        pg_data_t       *pgdat;
+        int     ret;
+
+        lock_system_sleep();
+        pgdat = hotadd_new_pgdat(nid, 0);
+        if (pgdat) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        node_set_online(nid);
+        ret = register_one_node(nid);
+        BUG_ON(ret);
+
+out:
+        unlock_system_sleep();
+        return ret;
+}
+
 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 int __ref add_memory(int nid, u64 start, u64 size)
 {