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Message-ID: <34652266-06a6-b076-dec4-2abfa4c1b01b@garloff.de>
Date:   Thu, 29 Sep 2022 09:00:01 +0200
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Subject: Re: nfs_scan_commit: BUG: unable to handle page fault for address:
 000000001d473c07
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Thorsten Leemhuis <regressions@leemhuis.info>,
        Sasha Levin <sashal@kernel.org>,
        "anna@kernel.org" <anna@kernel.org>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "it+linux-nfs@molgen.mpg.de" <it+linux-nfs@molgen.mpg.de>,
        "pmenzel@molgen.mpg.de" <pmenzel@molgen.mpg.de>,
        Trond Myklebust <trondmy@hammerspace.com>
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 <YzPvBLBTyISlNz4k@kroah.com>
Content-Language: en-US
From:   Kurt Garloff <kurt@garloff.de>
In-Reply-To: <YzPvBLBTyISlNz4k@kroah.com>
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Hi Greg,

On 28/09/2022 08:51, Greg KH wrote:
> On Tue, Sep 27, 2022 at 08:59:31PM +0200, Kurt Garloff wrote:
>> On 26/09/2022 08:00, Thorsten Leemhuis wrote:
>>
>>> Does cherry-picking commit 6e176d47160c ("NFSv4: Fixes for
>>>>>> nfs4_inode_return_delegation()") into 5.15.69 from the upstream
>>>>>> kernel
>>>>>> tree fix the problem?
>>>>>>
>>>>>> 8<---------------------------------------------------
>>>>>>   From 6e176d47160cec8bcaa28d9aa06926d72d54237c Mon Sep 17 00:00:00
>>>>>> 2001
>>>>>> From: Trond Myklebust <trond.myklebust@hammerspace.com>
>>>>>> Date: Sun, 10 Oct 2021 10:58:12 +0200
>>>>>> Subject: [PATCH] NFSv4: Fixes for nfs4_inode_return_delegation()
>>>>> […]
>>>>>
>>>>> Indeed with that commit, present since v5.16-rc1, we are unable to
>>>>> reproduce the issue, so it seems to be the fix. It looks like there
>>>>> are
>>>>> not a lot of 5.15 NFS users out there. ;-)
>>>>>
>>>> I believe this is a dependency that was introduced by the back port of
>>>> commit e591b298d7ec ("NFS: Save some space in the inode") into 5.15.68.
>>>> So the reason it wasn't seen is because the change is very recent.
>>> Side note: I wonder if that is causing this problem from Kurt as well:
>>> https://lore.kernel.org/all/f6755107-b62c-a388-0ab5-0a6633bf9082@garloff.de/
>> Looks like it:
>> After confirming that the 5.15.69 kernel worked again fine backing out
>> those last three NFS commits, I reapplied them and cherry-picked commit
>> 6e176d47160c as suggested. The kernel worked flawlessly thus far, so this
>> seems to indeed be a requirement for e591b298d7ec not to cause harm.
>> [...]
>> So by all means, Greg, please put this in the stable queue unless the
>> NFS wizards out there consider it safer to revert e591b298d7ec instead.
> Already queued up for the next 5.15.y release that will happen in a few
> hours, thanks for testing.

And -- unsurprisingly -- I can confirm that NFS in 5.15.71 does work again,
indeed.

Thanks!

-- 
Kurt Garloff <kurt@garloff.de>
Cologne, Germany