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Message-ID: <5772e3c6-d955-f504-40e5-d6f3be50087d@rothenpieler.org>
Date:   Fri, 20 Aug 2021 18:21:40 +0200
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Subject: Re: Spurious instability with NFSoRDMA under moderate load
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To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Olga Kornievskaia <aglo@umich.edu>,
        Dai Ngo <dai.ngo@oracle.com>
References: <4da3b074-a6be-d83f-ccd4-b151557066aa@rothenpieler.org>
 <e12c24fd-beaf-31ce-cb49-36ad32bd22b3@rothenpieler.org>
 <daae674a-84d4-de36-336d-693dc582e3ef@rothenpieler.org>
 <9355de20-921c-69e0-e5a4-733b64e125e1@rothenpieler.org>
 <a28b403e-42cf-3189-a4db-86d20da1b7aa@rothenpieler.org>
 <4BA2A532-9063-4893-AF53-E1DAB06095CC@oracle.com>
 <c8025457-7376-e1b7-bd6c-e5c6ee5d9ce7@rothenpieler.org>
 <141fdf51-2aa1-6614-fe4e-96f168cbe6cf@rothenpieler.org>
 <99DFF0B0-FE0F-4416-B3F6-1F9535884F39@oracle.com>
 <64F9A492-44B9-4057-ABA5-C8202828A8DD@oracle.com>
 <1b8a24a9-5dba-3faf-8b0a-16e728a6051c@rothenpieler.org>
 <5DD80ADC-0A4B-4D95-8CF7-29096439DE9D@oracle.com>
 <0444ca5c-e8b6-1d80-d8a5-8469daa74970@rothenpieler.org>
 <cc2f55cd-57d4-d7c3-ed83-8b81ea60d821@rothenpieler.org>
 <3AF4F6CA-8B17-4AE9-82E2-21A2B9AA0774@oracle.com>
 <4caff277-8e53-3c75-70c1-8938b2a26933@rothenpieler.org>
 <716B2A38-9705-41D7-969B-665EF90156C7@oracle.com>
 <D55A1FA5-71D4-4D37-9B88-E1733BEDBE47@oracle.com>
From:   Timo Rothenpieler <timo@rothenpieler.org>
In-Reply-To: <D55A1FA5-71D4-4D37-9B88-E1733BEDBE47@oracle.com>
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On 20.08.2021 17:12, Chuck Lever III wrote:
> OK, I think the issue with this reproducer was resolved
> completely with 6820bf77864d.
> 
> I went back and reviewed the traces from when the client got
> stuck after a long uptime. This looks very different from
> what we're seeing with 6820bf77864d. It involves CB_PATH_DOWN
> and BIND_CONN_TO_SESSION, which is a different scenario. Long
> story short, I don't think we're getting any more value by
> leaving 6820bf77864d reverted.
> 
> Can you re-apply that commit on your server, and then when
> the client hangs again, please capture with:
> 
> # trace-cmd record -e nfsd -e sunrpc -e rpcrdma
> 
> I'd like to see why the client's BIND_CONN_TO_SESSION fails
> to repair the backchannel session.
> 
> --
> Chuck Lever

The main system is still running a regular 5.12.19, but so far the issue 
has not come up again yet.
Given how long it takes, I'll report whenever it happens next. I have 
sadly not found a way to provoke it getting stuck yet.

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