On Tue, Feb 02, 2016 at 07:15:57AM +0000, Wenbo Wang wrote: > Jens, > > I did the following test to validate the issue. > > 1. Modify code as below to increase the chance of races. > Add 10s delay after nvme_dev_unmap() in nvme_dev_disable() > Add 10s delay before __nvme_submit_cmd()
If running sync IO, preempt is disabled. You can't just put a 10 second delay there. Wouldn't you hit a "scheduling while atomic" bug instead? If blk-mq is running the h/w context from its work queue, that might be a different issue. Maybe we can change the "cancel_delayed_work" to "cancel_delayed_work_sync" in blk_mq_stop_hw_queues. If there's still a window where blk-mq can insert a request after the driver requested to stop queues, I think we should try to close it with the block layer.
