Hi Jason,
Yes it is a bug to hang on bad SM lid. While root causing the hang, I thought it is better to add some logic that will prevent sending the packets with bad dlid in first place.
Thank you,
Sandeep
On Mon, Dec 18, 2017 at 07:26:58PM -0800, Dennis Dalessandro wrote:
> From: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@xxxxxxxxx>
>
> SA queries SM for class port info when there is a LID_CHANGE event.
>
> When a base lid is configured before fm is started ie when smlid is
> not yet assigned, SA handles the LID_CHANGE event and tries query SM
> with lid 0. This will cause an hang.
>
> [ 1106.958820] INFO: task kworker/2:0:23 blocked for more than 120 seconds.
> [ 1106.965082] Tainted: G O 4.12.0+ #1 [ 1106.969602] "echo 0 >
> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 1106.977227] kworker/2:0 D 0 23 2 0x00000000 [ 1106.977250]
> Workqueue: infiniband update_ib_cpi [ib_core] [ 1106.977261] Call
> Trace:
> [ 1106.977273] __schedule+0x28e/0x860
> [ 1106.977285] schedule+0x36/0x80
> [ 1106.977298] schedule_timeout+0x1a3/0x2e0 [ 1106.977310] ?
> radix_tree_iter_tag_clear+0x1b/0x20
> [ 1106.977322] ? idr_alloc+0x64/0x90
> [ 1106.977334] wait_for_completion+0xe3/0x140 [ 1106.977347] ?
> wake_up_q+0x80/0x80 [ 1106.977369] update_ib_cpi+0x163/0x210 [ib_core]
> [ 1106.977381] process_one_work+0x147/0x370 [ 1106.977394]
> worker_thread+0x4a/0x390 [ 1106.977406] kthread+0x109/0x140 [
> 1106.977418] ? process_one_work+0x370/0x370 [ 1106.977430] ?
> kthread_park+0x60/0x60 [ 1106.977443] ret_from_fork+0x22/0x30
>
> Always ensure a proper smlid is assigned before querying SM for cpi.
>
> Fixes: ee1c60b1bff ("IB/SA: Modify SA to implicitly cache Class Port
> info")
> Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> Signed-off-by: Venkata Sandeep Dhanalakota
> <venkata.s.dhanalakota@xxxxxxxxx>
> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>
Took it to for-next
Although I am unclear why a bad SM lid should cause a hang? Doesn't like seem like a bug unto itself?
Thanks,
Jason
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