nfs-bug when server for 9-Stable becomes client as well ?

[Vincent Hoffman]

On 06/07/2012 14:19, Arno J. Klaassen wrote:
> Hello,
>
> looks like I discouvered a probable bug in the nfs-code, very
> easy to reproduce in my setup :
>
>
>    Machine-1 : Today's 9-stable, exporting /files (ufs) and /z2 (zfs)
>
>    Machine-2 : 8-stable as of April the 10th exporting /raid1
>
> On Machine-1 I mount /raid1 (rw,nfsv3,intr,tcp,rsize=32768,wsize=32768)
> and start a script on this mount looping something like :
>
>   dd if=/dev/random of=BIG bs=1048576 count=${SIZE}
>   cp -fp BIG BIG2
>   cmp -x BIG BIG2
>
> I let this run for 24 hours (from time to time stressing Machine-1 with
> other scripts, including provoking heavy swapping), no problem at all.
>
> However, then I mount /z2 (rw,nfsv3,intr,tcp,rsize=32768,wsize=32768)
> on Machine-2, and *immediately* the above loop on Machine-1 fails :
>
>   Copying file ...cp: BIG: Permission denied
>
> No console messages this time, last time I got 
>
>   kernel: nfs_getpages: error 13
>   kernel: vm_fault: pager read error, pid 87803 (cmp)
>
> on Machine-1.
>
> I repeated this scenario by replacing Machine-2 with a good old
> 6-4-stable one, same outcome.
>
> Please tell me what I could do to nail this down a bit more.
Its possible (although not definite) that you have hit the a mountd bug
as documented in PRs

kern/131342
kern/136865

I've recently asked on -CURRENT about this and had a patch to try from
Rick, I'm testing it now but it doesnt seem to fix it for me, just
improve it alothough I'm trying to get enough runs to be a valid sample.
(see
http://docs.freebsd.org/cgi/getmsg.cgi?fetch=377627+0+archive/2012/freebsd-current/20120701.freebsd-current
)

What I did for my production nas was edit mount.c so it didnt send a
SIGHUP to mountd as suggested by rick, as it was easy to do and non
intrusive.

Vince

>
> Thanx in advance,
>
> Best, Arno
>
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