On 2025-05-29 16:13:23 -0600, Keith Busch wrote: > On Thu, May 29, 2025 at 03:49:28PM -0600, Mohamed Khalfella wrote: > > nvme-fc initiator hit hung_task with stacktrace above while handling > > request timeout call. The work thread is waiting for itself to finish > > which is never going to happen. From the stacktrace the nvme controller > > was in NVME_CTRL_CONNECTING state when nvme_fc_timeout() was called. > > We do not expect to get IO timeout call in NVME_CTRL_CONNECTING state > > because blk_sync_queue() must have been called on this queue before > > switching from NVME_CTRL_RESETTING to NVME_CTRL_CONNECTING. > > > > It turned out that blk_sync_queue() did not stop q->timeout_work from > > running as expected. nvme_fc_timeout() returned BLK_EH_RESET_TIMER > > causing q->timeout to be rearmed after it was canceled earlier. > > q->timeout queued q->timeout_work after the controller switched to > > NVME_CTRL_CONNECTING state causing deadlock above. > > > > Add QUEUE_FLAG_NOTIMEOUT queue flag to tell q->timeout not to queue > > q->timeout_work while queue is being synced. Update blk_sync_queue() to > > cancel q->timeout_work first and then cancel q->timeout. > > I feel like this is a nvme-fc problem that doesn't need the block layer > to handle. Just don't sync the queues within the timeout workqueue > context. Agreed on nvme-fc should not sync queues within timeout work, and I am testing a patch to fix nvme-fc. At the same time blk_sync_queue() should provide a guarantee that q->timeout_work will not run after the function returns, no?
