Description of problem: 
presumably problem with unlocking in Samba.

Samba Errors: smb.log locking/locking.c:do_unlock(279)
  PANIC: assert failed at locking/locking.c(279)
Kernel Errors: CIFS VFS: Send error in Close = -9

Version-Release number of selected component (if applicable):
samba-3.0.25b-1.el4_6.2 and as far as I can see in source code
the current samba-3.0.25b-1.el4_6.5 is affected, too

How reproducible:
regularly, depending on traffic and lock/unlock behaviour of application

Steps to Reproduce:
1. export F/S from RHEL4.6 using Samba
2. mount on RHEL4.6 Linux systems using CIFS
3. heavily use Unix file locking on mounted system 
  
Actual results:
smb log:
[2008/07/16 09:14:50, 0] locking/locking.c:do_unlock(279)
  PANIC: assert failed at locking/locking.c(279)
[2008/07/16 09:15:51, 0] locking/locking.c:do_unlock(279)
  PANIC: assert failed at locking/locking.c(279)
and problems on the client side:
Jul 16 xx:xx:xx  kernel:  CIFS VFS: Send error in Close = -9

The custom applications on the CIFS client systems are unhappy, too.

Expected results:
lock and unlock just work.

Additional info:

The following patch may resolve these errors:

Quote:
"Here's the fix - will be in 3.0.25c. Problem was an optimization
introduced to not read the locking tdb on file close for Windows
locks if we know there were none on the file - for POSIX locks
you can't count of course as one unlock can unlock many locked
regions. Fix attached."

http://lists.samba.org/archive/samba-technical/2007-July/054535.html
http://lists.samba.org/archive/samba-technical/2007-July/054534.html