Weird lockups when using NFSv4

[Fredrik Tolf]

On Thu, 2007-08-09 at 23:48 -0400, Trond Myklebust wrote:
> On Fri, 2007-08-10 at 05:11 +0200, Fredrik Tolf wrote:
> > On Fri, 2007-08-10 at 03:52 +0200, Fredrik Tolf wrote:
> > > I'll try and present the facts that I know right
> > > now and hope that someone will be able to help me a bit on the way.
> > 
> > Btw., I'm using Gentoo's Linux sources, version 2.6.21-r4. To my
> > knowledge, they should match 2.6.21.6 without any changes whatsoever to
> > the NFS code.
> 
> Could it be related to delegations? Have a look at
> the /proc/self/mountstats DELEGRETURN statistics on the various clients
> that might be sharing the same file...

Sorry, but I'm not sure what to look for (in fact, I hadn't even noticed
the file mountstats to begin with). The line you mentioned looks like
this:
> DELEGRETURN: 16140 16140 0 3880800 5219528 104716 31347 138315
Since I don't know the NFS implementation internals very well, though, I
cannot say that I know how to interpret it.

However, if the problem may lie in a file being used by more than one
clients simultaneously, I don't think that's the problem, because it
definitely happens with files that are used by only one clients. For
example, the dmesg I attached my original message comes from playing a
video clip, and that file was definitely not being used by any other
clients for a long time either before or after.

Fredrik Tolf