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Date: Fri, 23 Jan 2015 09:30:37 +0800
Message-ID: <CA+eFSM3yBoqpb-tjz_ztyUyUV9RQEATVJ6nBWJgXJmbXvjGgQQ@mail.gmail.com>
Subject: Re: General protection fault in iscsi_rx_thread_pre_handler
From: Gavin Guo <gavin.guo@canonical.com>
To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: linux-scsi@vger.kernel.org, target-devel@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>
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Hi Nicholas,

On Fri, Jan 23, 2015 at 1:35 AM, Nicholas A. Bellinger
<nab@linux-iscsi.org> wrote:
> On Thu, 2015-01-22 at 23:56 +0800, Gavin Guo wrote:
>> Hi Nicolas,
>>
>> On Thu, Jan 22, 2015 at 5:50 PM, Nicholas A. Bellinger
>> <nab@linux-iscsi.org> wrote:
>> > Hi Gavin,
>> >
>> > On Thu, 2015-01-22 at 06:38 +0800, Gavin Guo wrote:
>> >> Hi all,
>> >>
>> >> The general protection fault screenshot is attached.
>> >>
>> >> Summary:
>> >> The kernel is Ubuntu-3.13.0-39.66. I've done basic analysis and found
>> >> the fault is in list_del of iscsi_del_ts_from_active_list. And it
>> >> looks like deleting the iscsi_thread_set *ts two times. The point to
>> >> delete including iscsi_get_ts_from_inactive_list, was also checked but
>> >> still can't find the clue. Really appreciate if anyone can provide any
>> >> idea on the bug.
>> >>
>
> <SNIP>
>
>> >
>> > Thanks for your detailed analysis.
>> >
>> > A similar bug was reported off-list some months back by a person using
>> > iser-target + RoCE export on v3.12.y code.  Just to confirm, your
>> > environment is using traditional iscsi-target + TCP export, right..?
>>
>> I am sorry that I'm not an expert of the field and already google RoCE
>> on the internet but still don't really know what RoCE is. However, I
>> can provide the informations.  We used iscsiadm on the initiator side
>> and lio_node and tcm_node commands to create the targets for
>> connection. I think it should be normal  iscsi-target using TCP
>> export.
>>
>
> Yep, that would be traditional iscsi-target + TCP export.
>
>> >
>> > At the time, a different set of iser-target related changes ended up
>> > avoiding this issue on his particular setup, so we thought it was likely
>> > a race triggered by login failures specific to iser-target code.
>> >
>> > There was a untested patch (included inline below) to drop the legacy
>> > active_ts_list usage all-together, but IIRC he was not able to reproduce
>> > further so the patch didn't get picked up for mainline.
>> >
>> > If your able to reliability reproduce, please try with the following
>> > patch and let us know your progress.
>>
>> Thanks for your time reading the mail. I'll let you know the result.
>
> Just curious, are you able to reliability reproduce this bug in a VM..?

Thanks for your caring, the machine is on the customer side, I've
asked and now waiting for their response.

>
> --nab
>