nfs_getpages: error 4

[Dmitry Sivachenko]

Hello,

I am running a number of machines with /home mounted via nfs (FreeBSD 10.3-PRERELEASE #0 r294799, rw,bg,intr,soft).

Sometimes I get the following messages in syslog:

nfs_getpages: error 4
vm_fault: pager read error, pid NNN (myprog)

After that I see I lot of processes stuck in "pfault" state (these are computational processes which use some files from NFS mount), they use 0% of CPU after that.

On NFS server machine I see nothing strange in logs.  procstat -kk for such stuck processes shows:
 PID    TID COMM             TDNAME           KSTACK                       
85274 102056 myprog           -                mi_switch+0xbe sleepq_wait+0x3a _sleep+0x287 vm_waitpfault+0x8a vm_fault_hold+0xdd0 vm_fault+0x77 trap_pfault+0x180 trap+0x52c calltrap+0x8


What can be the reason of this?

Thanks.