1 files changed, 30 insertions, 6 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 2df8ddcb0ca0..619984fc07ec 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -480,6 +480,10 @@ static void cgwb_release_workfn(struct work_struct *work)
                                                 release_work);
         struct backing_dev_info *bdi = wb->bdi;
 
+        spin_lock_irq(&cgwb_lock);
+        list_del_rcu(&wb->bdi_node);
+        spin_unlock_irq(&cgwb_lock);
+
         wb_shutdown(wb);
 
         css_put(wb->memcg_css);
@@ -575,6 +579,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
                 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
                 if (!ret) {
                         atomic_inc(&bdi->usage_cnt);
+                        list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
                         list_add(&wb->memcg_node, memcg_cgwb_list);
                         list_add(&wb->blkcg_node, blkcg_cgwb_list);
                         css_get(memcg_css);
@@ -676,7 +681,7 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
 static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
 {
         struct radix_tree_iter iter;
-        struct bdi_writeback_congested *congested, *congested_n;
+        struct rb_node *rbn;
         void **slot;
 
         WARN_ON(test_bit(WB_registered, &bdi->wb.state));
@@ -686,9 +691,11 @@ static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
         radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
                 cgwb_kill(*slot);
 
-        rbtree_postorder_for_each_entry_safe(congested, congested_n,
-                                        &bdi->cgwb_congested_tree, rb_node) {
-                rb_erase(&congested->rb_node, &bdi->cgwb_congested_tree);
+        while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
+                struct bdi_writeback_congested *congested =
+                        rb_entry(rbn, struct bdi_writeback_congested, rb_node);
+
+                rb_erase(rbn, &bdi->cgwb_congested_tree);
                 congested->bdi = NULL;  /* mark @congested unlinked */
         }
 
@@ -764,15 +771,22 @@ static void cgwb_bdi_destroy(struct backing_dev_info *bdi) { }
 
 int bdi_init(struct backing_dev_info *bdi)
 {
+        int ret;
+
         bdi->dev = NULL;
 
         bdi->min_ratio = 0;
         bdi->max_ratio = 100;
         bdi->max_prop_frac = FPROP_FRAC_BASE;
         INIT_LIST_HEAD(&bdi->bdi_list);
+        INIT_LIST_HEAD(&bdi->wb_list);
         init_waitqueue_head(&bdi->wb_waitq);
 
-        return cgwb_bdi_init(bdi);
+        ret = cgwb_bdi_init(bdi);
+
+        list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
+
+        return ret;
 }
 EXPORT_SYMBOL(bdi_init);
 
@@ -823,7 +837,7 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi)
         synchronize_rcu_expedited();
 }
 
-void bdi_destroy(struct backing_dev_info *bdi)
+void bdi_unregister(struct backing_dev_info *bdi)
 {
         /* make sure nobody finds us on the bdi_list anymore */
         bdi_remove_from_list(bdi);
@@ -835,9 +849,19 @@ void bdi_destroy(struct backing_dev_info *bdi)
                 device_unregister(bdi->dev);
                 bdi->dev = NULL;
         }
+}
 
+void bdi_exit(struct backing_dev_info *bdi)
+{
+        WARN_ON_ONCE(bdi->dev);
         wb_exit(&bdi->wb);
 }
+
+void bdi_destroy(struct backing_dev_info *bdi)
+{
+        bdi_unregister(bdi);
+        bdi_exit(bdi);
+}
 EXPORT_SYMBOL(bdi_destroy);
 
 /*