1 files changed, 13 insertions, 5 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 85eb4d342ac5..089cc97aed3c 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -389,6 +389,11 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
         int nid;
         int ret;
         struct memory_notify arg;
+        /*
+         * mutex to protect zone->pageset when it's still shared
+         * in onlined_pages()
+         */
+        static DEFINE_MUTEX(zone_pageset_mutex);
 
         arg.start_pfn = pfn;
         arg.nr_pages = nr_pages;
@@ -415,12 +420,14 @@ 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(&zone_pageset_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(&zone_pageset_mutex);
                 printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
                         nr_pages, pfn);
                 memory_notify(MEM_CANCEL_ONLINE, &arg);
@@ -429,8 +436,12 @@ 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(&zone_pageset_mutex);
         setup_per_zone_wmarks();
         calculate_zone_inactive_ratio(zone);
         if (onlined_pages) {
@@ -438,10 +449,7 @@ 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();