On 10/26/2016 02:08 PM, Jakub Kicinski wrote:

On Wed, 26 Oct 2016 16:15:24 +0000, Yotam Gigi wrote:

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-----Original Message-----
From: Anna Schumaker [mailto:Anna.Schumaker@Netapp.com]
Sent: Wednesday, October 26, 2016 5:40 PM
To: Yotam Gigi <redacted>; Jakub Kicinski <redacted>; Andy
Adamson [off-list ref]; Anna Schumaker
[off-list ref]; linux-nfs@vger.kernel.org
Cc: netdev@vger.kernel.org; Trond Myklebust <redacted>;
Yotam Gigi [off-list ref]; mlxsw [off-list ref]
Subject: Re: nfs NULL-dereferencing in net-next

On 10/25/2016 01:19 PM, Yotam Gigi wrote:  

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-----Original Message-----
From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org]  

On  

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Behalf Of Jakub Kicinski
Sent: Monday, October 17, 2016 10:20 PM
To: Andy Adamson <redacted>; Anna Schumaker
[off-list ref]; linux-nfs@vger.kernel.org
Cc: netdev@vger.kernel.org; Trond Myklebust  

[off-list ref]  

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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  

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completely unusable.

I bisected it and got to the commit:

commit 04ea1b3e6d8ed4978bb608c1748530af3de8c274
Author: Andy Adamson [off-list ref]
Date:   Fri Sep 9 09:22:27 2016 -0400

    NFS add xprt switch addrs test to match client

    Signed-off-by: Andy Adamson [off-list ref]
    Signed-off-by: Anna Schumaker [off-list ref]  

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

HTH