Description of problem:
When accessing several files at the same time (eg Evolution), NFS halts and a kernel message is printed on all terminals.

When using evolution, this usually happens each 15 minutes.

The clients are Fedora 16 i686 connected to a RHEL 6.2 NFS server. Mount options are: rsize=8192,wsize=8192. We used to have mount option 'tcp' as well, but that lead to constant hickups. mtab lists:
{{SERVERIP}}:/home/ /home nfs4 rw,relatime,vers=4,rsize=8192,wsize=8192,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr={{CLIENTIP SAME SUBNET}},minorversion=0,local_lock=none,addr={{SERVERIP}} 0 0

Version-Release number of selected component (if applicable):
All systems are fully up to date.

How reproducible:
Happens very often.

Steps to Reproduce:
1. Start evolution, read some e-mails
2. Evolution hangs
3. Error message is printed on all terminals
  
Additional info:
Message from syslogd@takashima at Apr 18 12:28:48 ...
 kernel:[61466.297585] Process evolution (pid: 12662, ti=f099e000 task=f1bbd7f0 task.ti=f099e000)

Message from syslogd@takashima at Apr 18 12:28:48 ...
 kernel:[61466.297587] Stack:

Message from syslogd@takashima at Apr 18 12:28:48 ...
 kernel:[61466.297608] Call Trace:

Message from syslogd@takashima at Apr 18 12:28:48 ...
 kernel:[61466.297696] Code: ff 90 e9 88 fe ff ff 8d 74 26 00 8d bc 27 00 00 00 00 55 89 e5 3e 8d 74 26 00 f0 80 48 34 04 5d c3 90 55 89 e5 53 3e 8d 74 26 00 <8b> 48 dc 31 c0 85 c9 74 13 8b 59 20 83 e2 03 21 d3 39 d3 75 07 

Message from syslogd@takashima at Apr 18 12:28:48 ...
 kernel:[61466.297731] EIP: [<fbd31329>] nfs_have_delegation+0x9/0x30 [nfs] SS:ESP 0068:f099fec8