Re: WARNING at fs/nfs/write.c:743 nfs_inode_remove_request with -rc6

Weston Andros Adamson
2014-09-23T15:02:28Z

On Sep 23, 2014, at 10:59 AM, Weston Andros Adamson <dros@primarydata.com> wrote:

> On Sep 23, 2014, at 10:53 AM, Will Deacon <will.deacon@arm.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.

-dros