v4.14-rc5 NVMeOF regression?

[Bart Van Assche]

On Wed, 2017-10-18 at 08:26 +0300, Sagi Grimberg wrote:
> If you ran into a real deadlock, did you have any other output from
> hung_task watchdog? I do not yet understand the root cause from
> lockdep info provided.
>
> Also, do you know at which test-case this happened?

Hello Sagi,

Running test case 1 should be sufficient to trigger the deadlock. SysRq-w
produced the following output:

sysrq: SysRq : Show Blocked State
  task                        PC stack   pid father
kworker/u66:2   D    0   440      2 0x80000000
Workqueue: nvme-wq nvme_rdma_del_ctrl_work [nvme_rdma]
Call Trace:
 __schedule+0x3e9/0xb00
 schedule+0x40/0x90
 schedule_timeout+0x221/0x580
 io_schedule_timeout+0x1e/0x50
 wait_for_completion_io_timeout+0x118/0x180
 blk_execute_rq+0x86/0xc0
 __nvme_submit_sync_cmd+0x89/0xf0
 nvmf_reg_write32+0x4b/0x90 [nvme_fabrics]
 nvme_shutdown_ctrl+0x41/0xe0
 nvme_rdma_shutdown_ctrl+0xca/0xd0 [nvme_rdma]
 nvme_rdma_remove_ctrl+0x2b/0x40 [nvme_rdma]
 nvme_rdma_del_ctrl_work+0x25/0x30 [nvme_rdma]
 process_one_work+0x1fd/0x630
 worker_thread+0x1db/0x3b0
 kthread+0x11e/0x150
 ret_from_fork+0x27/0x40
01              D    0  2868   2862 0x00000000
Call Trace:
 __schedule+0x3e9/0xb00
 schedule+0x40/0x90
 schedule_timeout+0x260/0x580
 wait_for_completion+0x108/0x170
 flush_work+0x1e0/0x270
 nvme_rdma_del_ctrl+0x5a/0x80 [nvme_rdma]
 nvme_sysfs_delete+0x2a/0x40
 dev_attr_store+0x18/0x30
 sysfs_kf_write+0x45/0x60
 kernfs_fop_write+0x124/0x1c0
 __vfs_write+0x28/0x150
 vfs_write+0xc7/0x1b0
 SyS_write+0x49/0xa0
 entry_SYSCALL_64_fastpath+0x18/0xad

Bart.