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-rw-r--r--mm/page-writeback.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 155efca4c123..17403e3a7c89 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1148,6 +1148,19 @@ pause:
if (task_ratelimit)
break;
+ /*
+ * In the case of an unresponding NFS server and the NFS dirty
+ * pages exceeds dirty_thresh, give the other good bdi's a pipe
+ * to go through, so that tasks on them still remain responsive.
+ *
+ * In theory 1 page is enough to keep the comsumer-producer
+ * pipe going: the flusher cleans 1 page => the task dirties 1
+ * more page. However bdi_dirty has accounting errors. So use
+ * the larger and more IO friendly bdi_stat_error.
+ */
+ if (bdi_dirty <= bdi_stat_error(bdi))
+ break;
+
if (fatal_signal_pending(current))
break;
}