If request is marked as NVME_REQ_CANCELLED, we don't need to retry for requeuing it, and it should be completed immediately. Even simply from the flag name, it needn't to be requeued.
Otherwise, it is easy to cause IO hang when IO is timed out in case of PCI NVMe:
1) IO timeout is triggered, and nvme_timeout() tries to disable device(nvme_dev_disable) and reset controller(nvme_reset_ctrl)
2) inside nvme_dev_disable(), queue is frozen and quiesced, and try to cancel every request, but the timeout request can't be canceled since it is completed by __blk_mq_complete_request() in blk_mq_rq_timed_out().
3) this timeout req is requeued via nvme_complete_rq(), but can't be dispatched at all because queue is quiesced and hardware isn't ready, finally nvme_wait_freeze() waits for ever in nvme_reset_work().
Cc: "jianchao.wang" jianchao.w.wang@oracle.com Cc: Sagi Grimberg sagi@grimberg.me Cc: Keith Busch keith.busch@intel.com Cc: stable@vger.kernel.org Reported-by: Xiao Liang xiliang@redhat.com Signed-off-by: Ming Lei ming.lei@redhat.com --- drivers/nvme/host/core.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 0ff03cf95f7f..5cd713a164cb 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -210,6 +210,8 @@ static inline bool nvme_req_needs_retry(struct request *req) return false; if (nvme_req(req)->retries >= nvme_max_retries) return false; + if (nvme_req(req)->flags & NVME_REQ_CANCELLED) + return false; return true; }