1 files changed, 6 insertions, 1 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 65ab5c7067d9..43bc893470b4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1724,8 +1724,13 @@ static int ksm_memory_callback(struct notifier_block *self,
                 /*
                  * Keep it very simple for now: just lock out ksmd and
                  * MADV_UNMERGEABLE while any memory is going offline.
+                 * mutex_lock_nested() is necessary because lockdep was alarmed
+                 * that here we take ksm_thread_mutex inside notifier chain
+                 * mutex, and later take notifier chain mutex inside
+                 * ksm_thread_mutex to unlock it.   But that's safe because both
+                 * are inside mem_hotplug_mutex.
                  */
-                mutex_lock(&ksm_thread_mutex);
+                mutex_lock_nested(&ksm_thread_mutex, SINGLE_DEPTH_NESTING);
                 break;
 
         case MEM_OFFLINE: