freebsd stable - Mar 2016 - nfs_getpages: error 4

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.

05.03.2016 18:21, 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?
For example, if some processes running on NFS server box modify some files
"in-place"
and these files are opened by processes running on NFS client, that could be the
reason.
If so, change this so processes updating such files create new temporary
versions of them first
and then rename them atomically.

Eugene Grosbein