On Tue, Mar 19, 2019 at 08:10:22AM -0700, Bart Van Assche wrote:

On Tue, 2019-03-19 at 09:25 +0800, jianchao.wang wrote:

quoted

Do you mean this patch from Jens ?
https://marc.info/?l=linux-block&m=154534605914798&w=2

+	rcu_read_lock();
 	sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data);
+	rcu_read_unlock();

The busy_iter_fn could sleep for nvme
blk_mq_check_expired
  -> blk_mq_rq_timed_out
    -> q->mq_ops->timeout
       nvme_timeout
         -> nvme_dev_disable
            -> mutex_lock dev->shutdown_lock

Hi Jianchao,

I think that's an additional reason to rewrite NVMe error handling ...

Nonesense. Block timeout handling runs in a work queue precicesly so
handlers can actually do useful work in line with the notification.