mm: Add comment explaining task state setting in bdi_forker_thread()
CC: Wu Fengguang <fengguang.wu@intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 94a047b..a87da52 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -401,6 +401,13 @@
}
spin_lock_bh(&bdi_lock);
+ /*
+ * In the following loop we are going to check whether we have
+ * some work to do without any synchronization with tasks
+ * waking us up to do work for them. So we have to set task
+ * state already here so that we don't miss wakeups coming
+ * after we verify some condition.
+ */
set_current_state(TASK_INTERRUPTIBLE);
list_for_each_entry(bdi, &bdi_list, bdi_list) {