samba - Jul 2015 - smbd core-dumping when removing file; mis-configuration?

Hello List,

We've recently set up a new NAS box in our office, and I'm in the 
process of copying files over from our previous implementation.  Along 
the way, I'm taking the opportunity to prune certain details.  In so 
doing, I'm getting lots of errors returned to the client (rm, in this 
case), and seeing many apparent coredumps of smbd.

To copy and prune, I'm performing the moral equivalent of (with FROM as 
the mount point of the legacy server, and TO the mount point of the new 
server):

     for PROJECT in ...; do
        rsync -PHhaAmXrvW "$FROM/$PROJECT" "$TO/"
     done

"Oh, $THAT could be removed!"

     kevin at FROM $ rm -rf "$THAT/"
     kevin at TO   $ rm -rf "$THAT/"

The problem is that the rm command against the new NAS box returns a lot 
of lines like:

     rm: cannot remove '[snip to anonymize]/QualitySettings.asset': 
Input/output error

If I perform the action a second time, the files in question appear to 
be successfully removed.

On the new NAS box, I see this (representative snippet) repeated many 
times in the logs:

-----
     +-----------------------+
     |  NMBD debugging info  |
     +-----------------------+
     [backtrace full]
     No stack.

     [info registers]
     /usr/local/etc/samba.gdb:14: Error in sourced command file:
     The program has no registers now.

     +-----------------------+
     |  SMBD debugging info  |
     +-----------------------+
     [backtrace full]
     No stack.

     [info registers]
     /usr/local/etc/samba.gdb:14: Error in sourced command file:
     The program has no registers now.

     +---------------------------+
     |  WINBINDD debugging info  |
     +---------------------------+
     [backtrace full]
     No stack.

     [info registers]
     /usr/local/etc/samba.gdb:14: Error in sourced command file:
     The program has no registers now.
-----

The referenced line 14 is:

     info registers

Which to my untrained eye does not look suspicious.  I'm not sure where 
to place blame because Samba is clearly a high-profile, well-used 
project (meaning I must have misconfigured something), but I've always 
followed the rubric of "if it coredumps, it has a bug".

Does any of this look familiar to anyone?  Have I obviously flubbed some 
configuration item?  I'm hoping so, because I'd like to not have to 
discover some critical error in my implementation of Samba two months 
after I turn this puppy live for our office.

Many thanks for any help with this matter.

Kevin