netdev - RE: nfs NULL-dereferencing in net-next

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Message-ID: <DB3PR05MB0764F0409AE75E0172ABFE2EACAA0@DB3PR05MB0764.eurprd05.prod.outlook.com>
Date:   Thu, 27 Oct 2016 06:50:22 +0000
From:   Yotam Gigi <yotamg@...lanox.com>
To:     Anna Schumaker <Anna.Schumaker@...app.com>,
        Jakub Kicinski <kubakici@...pl>
CC:     Andy Adamson <andros@...app.com>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Trond Myklebust <Trond.Myklebust@...app.com>,
        Yotam Gigi <yotam.gi@...il.com>, mlxsw <mlxsw@...lanox.com>
Subject: RE: nfs NULL-dereferencing in net-next



>-----Original Message-----
>From: Anna Schumaker [mailto:Anna.Schumaker@...app.com]
>Sent: Wednesday, October 26, 2016 9:17 PM
>To: Jakub Kicinski <kubakici@...pl>
>Cc: Yotam Gigi <yotamg@...lanox.com>; Andy Adamson <andros@...app.com>;
>linux-nfs@...r.kernel.org; netdev@...r.kernel.org; Trond Myklebust
><Trond.Myklebust@...app.com>; Yotam Gigi <yotam.gi@...il.com>; mlxsw
><mlxsw@...lanox.com>
>Subject: Re: nfs NULL-dereferencing in net-next
>
>On 10/26/2016 02:08 PM, Jakub Kicinski wrote:
>> On Wed, 26 Oct 2016 16:15:24 +0000, Yotam Gigi wrote:
>>>> -----Original Message-----
>>>> From: Anna Schumaker [mailto:Anna.Schumaker@...app.com]
>>>> Sent: Wednesday, October 26, 2016 5:40 PM
>>>> To: Yotam Gigi <yotamg@...lanox.com>; Jakub Kicinski <kubakici@...pl>;
>Andy
>>>> Adamson <andros@...app.com>; Anna Schumaker
>>>> <Anna.Schumaker@...app.com>; linux-nfs@...r.kernel.org
>>>> Cc: netdev@...r.kernel.org; Trond Myklebust
><Trond.Myklebust@...app.com>;
>>>> Yotam Gigi <yotam.gi@...il.com>; mlxsw <mlxsw@...lanox.com>
>>>> Subject: Re: nfs NULL-dereferencing in net-next
>>>>
>>>> On 10/25/2016 01:19 PM, Yotam Gigi wrote:
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: netdev-owner@...r.kernel.org [mailto:netdev-
>owner@...r.kernel.org]
>>>> On
>>>>>> Behalf Of Jakub Kicinski
>>>>>> Sent: Monday, October 17, 2016 10:20 PM
>>>>>> To: Andy Adamson <andros@...app.com>; Anna Schumaker
>>>>>> <Anna.Schumaker@...app.com>; linux-nfs@...r.kernel.org
>>>>>> Cc: netdev@...r.kernel.org; Trond Myklebust
>>>> <Trond.Myklebust@...app.com>
>>>>>> Subject: nfs NULL-dereferencing in net-next
>>>>>>
>>>>>> Hi!
>>>>>>
>>>>>> I'm hitting this reliably on net-next, HEAD at 3f3177bb680f
>>>>>> ("fsl/fman: fix error return code in mac_probe()").
>>>>>
>>>>>
>>>>> I see the same thing. It happens constantly on some of my machines, making
>>>> them
>>>>> completely unusable.
>>>>>
>>>>> I bisected it and got to the commit:
>>>>>
>>>>> commit 04ea1b3e6d8ed4978bb608c1748530af3de8c274
>>>>> Author: Andy Adamson <andros@...app.com>
>>>>> Date:   Fri Sep 9 09:22:27 2016 -0400
>>>>>
>>>>>     NFS add xprt switch addrs test to match client
>>>>>
>>>>>     Signed-off-by: Andy Adamson <andros@...app.com>
>>>>>     Signed-off-by: Anna Schumaker <Anna.Schumaker@...app.com>
>>>>
>>>> Thanks for reporting on this everyone!  Does this patch help?
>>>
>>> Actually, I still see the same bug with the same trace.
>
>Well, it was worth a shot.  I'll keep poking at it.
>
>>
>> I rebuild the latest net-next and I'm not seeing the trace any more...
>> I'm only seeing this (with or without your patch):
>>
>> [   23.465877] NFS: set_pnfs_layoutdriver: cl_exchange_flags 0x0
>> [   23.473784] NFS: set_pnfs_layoutdriver: cl_exchange_flags 0x0
>> [   23.588890] NFS: set_pnfs_layoutdriver: cl_exchange_flags 0x0
>> [   23.596746] NFS: set_pnfs_layoutdriver: cl_exchange_flags 0x0
>> [   23.781574] NFS: set_pnfs_layoutdriver: cl_exchange_flags 0x0
>> [   23.789599] NFS: set_pnfs_layoutdriver: cl_exchange_flags 0x0
>
>Interesting, I get that too when I try to use NFS v4.1.  It's weird that the crash would
>stop happening like that, so maybe something is racy in this area.
>
>Thanks for testing, Yotam and Jakub!
>Anna

I just found out that it happens on any of my machines, once I put two nfs entries in
my fstab. If I put only one, I don't see the problem. 

I hope it might be helpful :)

>
>>
>> HTH
>>