1 files changed, 8 insertions, 3 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 1065b715ef64..67a33a5a1a93 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -604,10 +604,14 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 
         /*
          * Finally, kill the kernel threads. We don't need to be RCU
-         * safe anymore, since the bdi is gone from visibility.
+         * safe anymore, since the bdi is gone from visibility. Force
+         * unfreeze of the thread before calling kthread_stop(), otherwise
+         * it would never exet if it is currently stuck in the refrigerator.
          */
-        list_for_each_entry(wb, &bdi->wb_list, list)
+        list_for_each_entry(wb, &bdi->wb_list, list) {
+                wb->task->flags &= ~PF_FROZEN;
                 kthread_stop(wb->task);
+        }
 }
 
 /*
@@ -628,6 +632,8 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)
 void bdi_unregister(struct backing_dev_info *bdi)
 {
         if (bdi->dev) {
+                bdi_prune_sb(bdi);
+
                 if (!bdi_cap_flush_forker(bdi))
                         bdi_wb_shutdown(bdi);
                 bdi_debug_unregister(bdi);
@@ -697,7 +703,6 @@ void bdi_destroy(struct backing_dev_info *bdi)
                 spin_unlock(&inode_lock);
         }
 
-        bdi_prune_sb(bdi);
         bdi_unregister(bdi);
 
         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)