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SubjectRe: [PATCH] nvme-pci: not invoke nvme_remove_dead_ctrl when change state fails
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Hi Keith

On 06/20/2018 12:39 AM, Keith Busch wrote:
> On Tue, Jun 19, 2018 at 04:30:50PM +0800, Jianchao Wang wrote:
>> There is race between nvme_remove and nvme_reset_work that can
>> lead to io hang.
>>
>> nvme_remove nvme_reset_work
>> -> change state to DELETING
>> -> fail to change state to LIVE
>> -> nvme_remove_dead_ctrl
>> -> nvme_dev_disable
>> -> quiesce request_queue
>> -> queue remove_work
>> -> cancel_work_sync reset_work
>> -> nvme_remove_namespaces
>> -> splice ctrl->namespaces
>> nvme_remove_dead_ctrl_work
>> -> nvme_kill_queues
>> -> nvme_ns_remove do nothing
>> -> blk_cleanup_queue
>> -> blk_freeze_queue
>> Finally, the request_queue is quiesced state when wait freeze,
>> we will get io hang here.
>>
>> In fact, when fails to change state in nvme_reset_work, the only
>> reason is someone has changed state to DELETING. So it is not
>> necessary to invoke nvme_remove_dead_ctrl in that case.
>>
>> Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
>
> Good catch. I think the fix should either have the nvme_dev_disable set
> shutdown to true to indicate the controller isn't coming back online, or
> move the nvme_kill_queues inside nvme_remove_dead_ctrl.

Yes,just not invoking nvme_remove_dead_ctrl when change state fails couldn't fix the hole completely.
I prefer to move nvme_kill_queues from nvme_remove_dead_ctrl_work to nvme_remove_dead_ctrl.
Will post the V2 version based on this.


Thanks
Jianchao

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