NFS4 Client hangs when copying large files as of kernel version 4.4

[Bünnemann, Thomas]

NFS4 Client hangs when copying large files as of kernel version 4.4 

Full description of the problem/report: 
When doing simple copy-jobs with large files (f.ex. partition Images > 4
GByte filesize) the file transfer stalls after about 2 -16 GByte has passed
to the NFS-client.
No problems using kernel-versions up to kernel 4.2. 

Autonegotiated NFS-mount-values are still the same between 4.2 and
4.4/4.7rc5

server:/informatik/ab on /informatik/ab type nfs4
(rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,
port=0,timeo=600,retrans=2,sec=krb5,clientaddr=134.100.9.19,local_lock=none,
addr=XXX.XXX.XXX.XXX)

Keywords (i.e., modules, networking, kernel): 

Kernel version (from /proc/version): 
Linux version 4.7.0-040700rc5-generic (kernel@tangerine) (gcc version 5.4.0
20160609 (Ubuntu 5.4.0-4ubuntu1) ) #201606262232 SMP Mon Jun 27 02:34:07 UTC
2016


A small shell script or example program which triggers the problem: 
/informatik/ab/backup/ contains 8 files - each about 4Gbyte in size, simple
command:
'cp /informatik/ab/backup/*.ghs /tmp'


Regards,

Thomas Bünnemann
Universität Hamburg, FB Informatik
Rechenzentrum
Vogt-Kölln-Str. 30
22527 Hamburg

Tel.: ++49 40 42883-2278
Fax: ++49 40 42883-2241

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