writeback: fix memory leak in wb_queue_work()
[ Upstream commit 4a3a485b1ed0e109718cc8c9d094fa0f552de9b2 ]
When WB_registered flag is not set, wb_queue_work() skips queuing the
work, but does not perform the necessary clean up. In particular, if
work->auto_free is true, it should free the memory.
The leak condition can be reprouced by following these steps:
mount /dev/sdb /mnt/sdb
/* In qemu console: device_del sdb */
umount /dev/sdb
Above will result in a wb_queue_work() call on an unregistered wb and
thus leak memory.
Reported-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 05713a5..0703a11 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -173,19 +173,33 @@
spin_unlock_bh(&wb->work_lock);
}
+static void finish_writeback_work(struct bdi_writeback *wb,
+ struct wb_writeback_work *work)
+{
+ struct wb_completion *done = work->done;
+
+ if (work->auto_free)
+ kfree(work);
+ if (done && atomic_dec_and_test(&done->cnt))
+ wake_up_all(&wb->bdi->wb_waitq);
+}
+
static void wb_queue_work(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
trace_writeback_queue(wb, work);
- spin_lock_bh(&wb->work_lock);
- if (!test_bit(WB_registered, &wb->state))
- goto out_unlock;
if (work->done)
atomic_inc(&work->done->cnt);
- list_add_tail(&work->list, &wb->work_list);
- mod_delayed_work(bdi_wq, &wb->dwork, 0);
-out_unlock:
+
+ spin_lock_bh(&wb->work_lock);
+
+ if (test_bit(WB_registered, &wb->state)) {
+ list_add_tail(&work->list, &wb->work_list);
+ mod_delayed_work(bdi_wq, &wb->dwork, 0);
+ } else
+ finish_writeback_work(wb, work);
+
spin_unlock_bh(&wb->work_lock);
}
@@ -1875,16 +1889,9 @@
set_bit(WB_writeback_running, &wb->state);
while ((work = get_next_work_item(wb)) != NULL) {
- struct wb_completion *done = work->done;
-
trace_writeback_exec(wb, work);
-
wrote += wb_writeback(wb, work);
-
- if (work->auto_free)
- kfree(work);
- if (done && atomic_dec_and_test(&done->cnt))
- wake_up_all(&wb->bdi->wb_waitq);
+ finish_writeback_work(wb, work);
}
/*