1 files changed, 7 insertions, 0 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index cafcd743118..3ad5e3fbf57 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -285,6 +285,13 @@ static void blkg_destroy_all(struct request_queue *q)
                 blkg_destroy(blkg);
                 spin_unlock(&blkcg->lock);
         }
+
+        /*
+         * root blkg is destroyed.  Just clear the pointer since
+         * root_rl does not take reference on root blkg.
+         */
+        q->root_blkg = NULL;
+        q->root_rl.blkg = NULL;
 }
 
 static void blkg_rcu_free(struct rcu_head *rcu_head)