Messages in this thread | | | From | Hannes Reinecke <> | Subject | Re: [PATCH v4 6/8] nvme-fc: fix controller reset hang during traffic | Date | Wed, 4 Aug 2021 09:23:49 +0200 |
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On 8/2/21 1:26 PM, Daniel Wagner wrote: > From: James Smart <jsmart2021@gmail.com> > > commit fe35ec58f0d3 ("block: update hctx map when use multiple maps") > exposed an issue where we may hang trying to wait for queue freeze > during I/O. We call blk_mq_update_nr_hw_queues which may attempt to freeze > the queue. However we never started queue freeze when starting the > reset, which means that we have inflight pending requests that entered the > queue that we will not complete once the queue is quiesced. > > So start a freeze before we quiesce the queue, and unfreeze the queue > after we successfully connected the I/O queues (the unfreeze is already > present in the code). blk_mq_update_nr_hw_queues will be called only > after we are sure that the queue was already frozen. > > This follows to how the pci driver handles resets. > > This patch added logic introduced in commit 9f98772ba307 "nvme-rdma: fix > controller reset hang during traffic". > > Signed-off-by: James Smart <jsmart2021@gmail.com> > CC: Sagi Grimberg <sagi@grimberg.me> > [dwagner: call nvme_unfreeze() unconditionally in > nvme_fc_recreate_io_queues() to match the nvme_start_freeze()] > Tested-by: Daniel Wagner <dwagner@suse.de> > Reviewed-by: Daniel Wagner <dwagner@suse.de> > --- > drivers/nvme/host/fc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c > index 133b87db4f1d..b292af0fd655 100644 > --- a/drivers/nvme/host/fc.c > +++ b/drivers/nvme/host/fc.c > @@ -2486,6 +2486,7 @@ __nvme_fc_abort_outstanding_ios(struct nvme_fc_ctrl *ctrl, bool start_queues) > * (but with error status). > */ > if (ctrl->ctrl.queue_count > 1) { > + nvme_start_freeze(&ctrl->ctrl); > nvme_stop_queues(&ctrl->ctrl); > nvme_sync_io_queues(&ctrl->ctrl); > blk_mq_tagset_busy_iter(&ctrl->tag_set, > @@ -2966,8 +2967,8 @@ nvme_fc_recreate_io_queues(struct nvme_fc_ctrl *ctrl) > return -ENODEV; > } > blk_mq_update_nr_hw_queues(&ctrl->tag_set, nr_io_queues); > - nvme_unfreeze(&ctrl->ctrl); > } > + nvme_unfreeze(&ctrl->ctrl); > > ret = nvme_fc_create_hw_io_queues(ctrl, ctrl->ctrl.sqsize + 1); > if (ret) > There still is now an imbalance, as we're always calling 'nvme_unfreeze()' (irrespective on the number of queues), but will only call 'nvme_start_freeze()' if we have more than one queue.
This might lead to an imbalance on the mq_freeze_depth counter. Wouldn't it be better to move the call to 'nvme_start_freeze()' out of the if() condition to avoid the imbalance?
Cheers,
Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
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