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

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Date:	Tue, 23 Sep 2014 15:53:56 +0100
From:	Will Deacon <will.deacon@....com>
To:	Weston Andros Adamson <dros@...marydata.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 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.

Will
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