linux-kernel - Re: WARNING at fs/nfs/write.c:743 nfs_inode_remove

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Date:	Tue, 23 Sep 2014 11:08:36 -0400
From:	Weston Andros Adamson <dros@...marydata.com>
To:	Will Deacon <will.deacon@....com>
Cc:	Peng Tao <tao.peng@...marydata.com>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	linux-nfs list <linux-nfs@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: WARNING at fs/nfs/write.c:743 nfs_inode_remove_request with -rc6

On Sep 23, 2014, at 11:02 AM, Weston Andros Adamson <dros@...marydata.com> wrote:

> On Sep 23, 2014, at 10:59 AM, Weston Andros Adamson <dros@...marydata.com> wrote:
> 
>> On Sep 23, 2014, at 10:53 AM, Will Deacon <will.deacon@....com> wrote:
>> 
>>> On Tue, Sep 23, 2014 at 02:59:38PM +0100, Will Deacon wrote:
>>>> On Tue, Sep 23, 2014 at 02:33:06PM +0100, Weston Andros Adamson wrote:
>>>>> Any more info on how to reproduce this would be really great. Unfortunately I don’t
>>>>> have access to an arm64 system.
>>>> 
>>>> I've not spotted a pattern other than using 64k pages, yet. If I manage to
>>>> get a reproducer, I'll let you know.
>>>> 
>>>>> If it’s possible, could we get a packet trace around when this happens? This is pure
>>>>> speculation, but this might have something to do the resend path - a commit fails
>>>>> and all the requests on the commit list have to be resent.
>>>> 
>>>> Sure, once I can reproduce it reliably, then I'll try to do that.
>>> 
>>> Right, a bunch of DDing from /dev/zero over an ssh session triggers this
>>> very quickly. I've put a binary tcpdump here:
>>> 
>>> http://www.willdeacon.ukfsn.org/bitbucket/oopsen/nfs/tcpdump.bin
>>> 
>>> You may want to filter out the ssh packets. The only `interesting' thing to
>>> me is a retransmission about half way through, but I don't know what I'm
>>> looking for.
>>> 
>>> The NFS server is 10.1.203.204 and the client is 10.1.203.24.
>> 
>> Thanks! You are using NFSv2, so there are no commits - that rules out my hunch.
> 
> Wait a second - the whole point of this extra reference (that the WARN_ON_ONCE is
> related to) is to handle the pass off to commit lists.
> 
> Maybe I’m just doing the wrong thing here with NFSv2!
> 
> More soon.

Actually, can you see if this is reproducible with NFSv3?

Thanks,

-dros

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