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From: Sagi Grimberg <sagi@grimberg.me>
To: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Subject: Re: blktests failures with v6.4
Date: Sun, 9 Jul 2023 17:32:38 +0300	[thread overview]
Message-ID: <165eceaa-55d4-f9c7-7e02-18115e6df6fe@grimberg.me> (raw)
In-Reply-To: <lkmloyrqpebispffur5udxdiubmevvodtsvnap3jz7tv5ihstr@jg7ejye3bein>


> #3: nvme/003 (fabrics transport)
> 
>     When nvme test group is run with trtype=rdma or tcp, the test case fails
>     due to lockdep WARNING "possible circular locking dependency detected".
>     Reported in May/2023. Bart suggested a fix for trytpe=rdma [4] but it
>     needs more discussion.
> 
>     [4] https://lore.kernel.org/linux-nvme/20230511150321.103172-1-bvanassche@acm.org/

This patch is unfortunately incorrect and buggy.

This will likely make the issue go away, but adds another
old issue where a client can DDOS a target by bombarding it
with connect/disconnect. When releases are async and we don't
have any back-pressure, it is likely to happen.
--
diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index 4597bca43a6d..8b4f4aa48206 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -1582,11 +1582,6 @@ static int nvmet_rdma_queue_connect(struct 
rdma_cm_id *cm_id,
                 goto put_device;
         }

-       if (queue->host_qid == 0) {
-               /* Let inflight controller teardown complete */
-               flush_workqueue(nvmet_wq);
-       }
-
         ret = nvmet_rdma_cm_accept(cm_id, queue, &event->param.conn);
         if (ret) {
                 /*
diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 868aa4de2e4c..c8cfa19e11c7 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -1844,11 +1844,6 @@ static u16 nvmet_tcp_install_queue(struct 
nvmet_sq *sq)
         struct nvmet_tcp_queue *queue =
                 container_of(sq, struct nvmet_tcp_queue, nvme_sq);

-       if (sq->qid == 0) {
-               /* Let inflight controller teardown complete */
-               flush_workqueue(nvmet_wq);
-       }
-
         queue->nr_cmds = sq->size * 2;
         if (nvmet_tcp_alloc_cmds(queue))
                 return NVME_SC_INTERNAL;
--


  reply	other threads:[~2023-07-09 14:32 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-07  7:27 blktests failures with v6.4 Shinichiro Kawasaki
2023-07-09 14:32 ` Sagi Grimberg [this message]
2023-07-13  1:22   ` Shinichiro Kawasaki
2023-07-13  7:48     ` Sagi Grimberg
2023-07-13  8:41       ` Hannes Reinecke
2023-07-13 10:16         ` Sagi Grimberg

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