From: Chunguang Xu chunguang.xu@shopee.com
[ Upstream commit de105068fead55ed5c07ade75e9c8e7f86a00d1d ]
We found a issue on production environment while using NVMe over RDMA, admin_q reconnect failed forever while remote target and network is ok. After dig into it, we found it may caused by a ABBA deadlock due to tag allocation. In my case, the tag was hold by a keep alive request waiting inside admin_q, as we quiesced admin_q while reset ctrl, so the request maked as idle and will not process before reset success. As fabric_q shares tagset with admin_q, while reconnect remote target, we need a tag for connect command, but the only one reserved tag was held by keep alive command which waiting inside admin_q. As a result, we failed to reconnect admin_q forever. In order to fix this issue, I think we should keep two reserved tags for admin queue.
Fixes: ed01fee283a0 ("nvme-fabrics: only reserve a single tag") Signed-off-by: Chunguang Xu chunguang.xu@shopee.com Reviewed-by: Sagi Grimberg sagi@grimberg.me Reviewed-by: Chaitanya Kulkarni kch@nvidia.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Keith Busch kbusch@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/core.c | 6 ++++-- drivers/nvme/host/fabrics.h | 7 ------- 2 files changed, 4 insertions(+), 9 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index d4564a2517eb5..012c8b3f5f9c9 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4246,7 +4246,8 @@ int nvme_alloc_admin_tag_set(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set, set->ops = ops; set->queue_depth = NVME_AQ_MQ_TAG_DEPTH; if (ctrl->ops->flags & NVME_F_FABRICS) - set->reserved_tags = NVMF_RESERVED_TAGS; + /* Reserved for fabric connect and keep alive */ + set->reserved_tags = 2; set->numa_node = ctrl->numa_node; set->flags = BLK_MQ_F_NO_SCHED; if (ctrl->ops->flags & NVME_F_BLOCKING) @@ -4315,7 +4316,8 @@ int nvme_alloc_io_tag_set(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set, if (ctrl->quirks & NVME_QUIRK_SHARED_TAGS) set->reserved_tags = NVME_AQ_DEPTH; else if (ctrl->ops->flags & NVME_F_FABRICS) - set->reserved_tags = NVMF_RESERVED_TAGS; + /* Reserved for fabric connect */ + set->reserved_tags = 1; set->numa_node = ctrl->numa_node; set->flags = BLK_MQ_F_SHOULD_MERGE; if (ctrl->ops->flags & NVME_F_BLOCKING) diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h index 82e7a27ffbde3..80e15ad3936f3 100644 --- a/drivers/nvme/host/fabrics.h +++ b/drivers/nvme/host/fabrics.h @@ -18,13 +18,6 @@ /* default is -1: the fail fast mechanism is disabled */ #define NVMF_DEF_FAIL_FAST_TMO -1
-/* - * Reserved one command for internal usage. This command is used for sending - * the connect command, as well as for the keep alive command on the admin - * queue once live. - */ -#define NVMF_RESERVED_TAGS 1 - /* * Define a host as seen by the target. We allocate one at boot, but also * allow the override it when creating controllers. This is both to provide