[Samba] hanging smbd(s) revisited

Fermin Molina fermin at asic.udl.es
Wed Mar 1 13:09:10 GMT 2006

On Wed, 2006-03-01 at 09:57 +0000, Matt Johnson wrote:
> On Tue, 28 Feb 2006, Fermin Molina wrote:
> >>>> Just to add -- our fcntl locking issue is on Linux, we've
> >>>> seen it on 2.6.9, and, running Mandrake 10.2.
> >>>> locking.tdb is on a local disk. All smbd child processes are
> >>>> blocked on apparently the same fcntl when it happens.
> >>>
> >>> Hmmm...ok.  That ruins my theory.  I thought you were on AIX
> >>> as well.  And just to make sure, you are running Samba 3.0.21b
> >>> as well?
> >>
> >> Correct -- 3.0.21b on Linux 2.6. We had the same problem with 3.0.20 but
> >> it was MUCH more frequent... 3.0.21b seems to have reduced the frequency
> >> of the problem occurring but it does still seem to be there.
> >
> > I have had exactly the same problem. I reported that in thread "Samba
> > daemons hang trying to lock locking.tdb", about Jan 25.
> >
> > I had a NFS mount from another server and then shared with samba. I
> > moved the information on that server localy to the Samba server
> > (avoiding NFS). All goes ok from that change.
> >
> > I don't understand why it works, because all smbd daemons were hanging
> > in the previously commented fcntl call, that locks "locking.tdb" (that
> > was located in local filesystem, not in any NFS mounted shares).
> >
> > I'm using FC4 with last updates (kernel included) and samba 3.0.21b.
> That's the one. We are indeed sharing volumes from the Samba server 
> which have been mounted via NFS, perhaps this is indeed an issue? 

I don't know exactly, but when I moved the information from NFS servers
to local storage, the problems disappeared.

> Something subtle with regard to tdb locking deadlocking in very specific 
> cases for samba-reshared NFS filesystems? (And yes, our locking.tdb is 
> on a local /var.)

I cannot find any explanation for this behaviour...

> To reiterate... the fcntl64 spins in a blocking wait, so we never see an 
> error unfortunately. 

IMHO, it's a hard to find problem. I tried to log 10 samba, but I
couldn't find any clue.

> It is always one of the 1-byte locks in locking.tdb 
> which it jams on. Also, no change to this behaviour from 3.0.20 through 
> 3.0.21b -- all have been broken, although 3.0.20 seemed to break more 
> frequently than 3.0.21b.


Fermin Molina Ibarz
Tècnic sistemes - ASIC
Universitat de Lleida
Tel: +34 973 702151
GPG: 0x060F857A

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