[Samba] Constant error messages about failure to remove oplock

Shyam Kaushik shyam at zadarastorage.com
Thu Jul 9 07:39:05 UTC 2015

Hi Volker,

Yes this problem happens when we have "kernel oplocks = no". This happened
constantly in one of production systems & so we disabled level2-oplock
/set kernel-oplocks=yes (to avoid this issue). So unfortunately don’t have
an environment where it reproduces now & cannot capture strace.

I modified smbtorture/smb2 to do a test exactly like the tcpdump trace,
but the problem doesn’t happen. One thing is we don’t have session
create/tree-connect captured for the below problematic case. Do you think
it can have any influence on this (like varied parameters negotiated at
session establish)?

Also one difference b/n the smbtorture/smb2 test that I wrote is, in the
tcpdump I see that when the original problem happened, in SMB2/create
response, samba returned allocation-size=1MB whereas in my test, this is
not returned. I am not sure how this can happen as SMB2 create request in
tcpdump has
	ExtraInfo DHnQ MxAc QFid
(i.e. no ALSI specified in it). Any thoughts?

Thanks for your inputs!


-----Original Message-----
From: Volker Lendecke [mailto:Volker.Lendecke at SerNet.DE]
Sent: Thursday, July 09, 2015 12:51 PM
To: Shyam Kaushik
Cc: samba at lists.samba.org
Subject: Re: [Samba] Constant error messages about failure to remove

On Thu, Jul 09, 2015 at 10:39:58AM +0530, Shyam Kaushik wrote:
> Hi All,
> Need your help/inputs on what could be the probable cause/how to debug
> this further.
> We are using samba-4.0.25 & expose a share that has oplocks enabled & no
> kernel-oplocks set. We constantly see these messages in samba logs
> 	[2015/06/25 03:05:30.593150,  0, pid=1581, class=locking]
> ../source3/smbd/oplock_linux.c:184(linux_release_kernel_oplock)
> 	  linux_release_kernel_oplock: Error when removing kernel oplock
> on file ~test.pst.tmp, file_id = 10fcbd:4a9ff1c:0, gen_id = 3680654993.
> Error was Resource temporarily unavailable

Do you have "kernel oplocks = no" set? Then this is
surprising to see. If you can reproduce it, can you send the
output of

strace -ttT -p <smbd-pid>

for such an smbd from before opening the file to the error?


Volker Lendecke

SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de

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