On Wed, May 23, 2018 at 08:35:40AM -0600, Keith Busch wrote: > On Wed, May 23, 2018 at 08:34:48AM +0800, Ming Lei wrote: > > Let's consider the normal NVMe timeout code path: > > > > 1) one request is timed out; > > > > 2) controller is shutdown, this timed-out request is requeued from > > nvme_cancel_request(), but can't dispatch because queues are quiesced > > > > 3) reset is done from another context, and this request is dispatched > > again, and completed exactly before returning EH_HANDLED to blk-mq, but > > its state isn't updated to COMPLETE yet. > > > > 4) then double completions are done from both normal completion and timeout > > path. > > We're definitely fixing this, but I must admit that's an impressive > cognitive traversal across 5 thread contexts to arrive at that race. :)
It can be only 2 thread contexts if requeue is done on polled request from nvme_timeout(), :-) Thanks, Ming
