2 files changed, 6 insertions, 3 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 2427706f78b4..68c569fcbb66 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -694,7 +694,7 @@ typedef struct pglist_data {
                                              range, including holes */
         int node_id;
         wait_queue_head_t kswapd_wait;
-        struct task_struct *kswapd;
+        struct task_struct *kswapd;     /* Protected by lock_memory_hotplug() */
         int kswapd_max_order;
         enum zone_type classzone_idx;
 } pg_data_t;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eeb3bc9d1d36..661576324c7f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2955,14 +2955,17 @@ int kswapd_run(int nid)
 }
 
 /*
- * Called by memory hotplug when all memory in a node is offlined.
+ * Called by memory hotplug when all memory in a node is offlined.  Caller must
+ * hold lock_memory_hotplug().
  */
 void kswapd_stop(int nid)
 {
         struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
 
-        if (kswapd)
+        if (kswapd) {
                 kthread_stop(kswapd);
+                NODE_DATA(nid)->kswapd = NULL;
+        }
 }
 
 static int __init kswapd_init(void)