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-rw-r--r--block/blk-cgroup.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 6ce36ff98a41..3dc60fc441cb 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)
@@ -326,6 +333,9 @@ struct request_list *__blk_queue_next_rl(struct request_list *rl,
*/
if (rl == &q->root_rl) {
ent = &q->blkg_list;
+ /* There are no more block groups, hence no request lists */
+ if (list_empty(ent))
+ return NULL;
} else {
blkg = container_of(rl, struct blkcg_gq, rl);
ent = &blkg->q_node;