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

Will Deacon
2014-09-23T14:53:52Z

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