flusher: Fix PF_FROZEN race

To touch task->flags directly is racy. thaw_process() still has race
(changing non_current->flags, but this is another issue) though, I think
it's much better off.

So, use thaw_process() instead.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 67a33a5a1a93..0e8ca0347707 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -609,7 +609,7 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
          * it would never exet if it is currently stuck in the refrigerator.
          */
         list_for_each_entry(wb, &bdi->wb_list, list) {
-                wb->task->flags &= ~PF_FROZEN;
+                thaw_process(wb->task);
                 kthread_stop(wb->task);
         }
 }