several wired errors with samba4

Andrew Bartlett abartlet at samba.org
Thu Feb 26 18:04:38 MST 2009 

On Thu, 2009-02-26 at 16:14 +0300, Matthieu Patou wrote:
> Hello andrew,
> 
> I added yesterday the trace and today I got several traces (today I had 
> severals errors because a user has been using a bit more than usual the 
> server) (but it's still underloaded).
> 
> 
> > If you add a call to call_backtrace() in the case where we get this
> > error (where you print the uid at the moment), then we can see what the
> > call stack is, and try to debug this further.

Thank you *very* much. This is really, really useful debugging data.

In short, changing UIDs and nested event loops are a recipe for chaos. 

We need to not restart the main event loop in the
wbc_xids_to_sids_recv() call, or rework the 'change to user' code to
return to root before this call is made. 

If we must loop here, we should ensure we never call messaging_init(),
but instead have the message context already ready.

> pvfs_oplock_break: sending oplock break level 1 for 
> '\scripts\helpers.vbs' 0xa820280
> [Thu Feb 26 15:22:00 2009 MSK, 0 ../lib/util/fault.c:62:call_backtrace()]
> BACKTRACE: 35 stack frames:
>   #0 /usr/local/samba/sbin/samba(call_backtrace+0x2b) [0x898806b]
>   #1 /usr/local/samba/sbin/samba(messaging_init+0x275) [0x8889206]
>   #2 /usr/local/samba/sbin/samba [0x85b06f9]
>   #3 /usr/local/samba/sbin/samba [0x897dda5]
>   #4 /usr/local/samba/sbin/samba [0x85b08ba]
>   #5 /usr/local/samba/sbin/samba [0x889469a]
>   #6 /usr/local/samba/sbin/samba [0x8894e16]
>   #7 /usr/local/samba/sbin/samba(event_loop_once+0x16) [0x88914e1]
>   #8 /usr/local/samba/sbin/samba(composite_wait+0x40) [0x8890bc1]
>   #9 /usr/local/samba/sbin/samba(wbc_xids_to_sids_recv+0x24) [0x84c8fdd]
>   #10 /usr/local/samba/sbin/samba [0x84c56bb]
>   #11 /usr/local/samba/sbin/samba(pvfs_acl_query+0xf0) [0x84c5ffa]
>   #12 /usr/local/samba/sbin/samba [0x84b7f16]
>   #13 /usr/local/samba/sbin/samba(pvfs_qfileinfo+0xf7) [0x84b8305]
>   #14 /usr/local/samba/sbin/samba(ntvfs_next_qfileinfo+0x5e) [0x84aa794]
>   #15 /usr/local/samba/sbin/samba [0x84ecaaf]
>   #16 /usr/local/samba/sbin/samba(ntvfs_qfileinfo+0x55) [0x84a99a2]
>   #17 /usr/local/samba/sbin/samba [0x8441bb5]
>   #18 /usr/local/samba/sbin/samba [0x84424e3]
>   #19 /usr/local/samba/sbin/samba [0x8442c5f]
>   #20 /usr/local/samba/sbin/samba(smbsrv_reply_nttrans+0x29c) [0x8442fa1]
>   #21 /usr/local/samba/sbin/samba [0x843f50d]
>   #22 /usr/local/samba/sbin/samba(smbsrv_recv_smb_request+0x594) [0x843f027]
>   #23 /usr/local/samba/sbin/samba(packet_recv+0x65b) [0x86902db]
>   #24 /usr/local/samba/sbin/samba [0x842e8eb]
>   #25 /usr/local/samba/sbin/samba [0x85b02bd]
>   #26 /usr/local/samba/sbin/samba [0x85b0338]
>   #27 /usr/local/samba/sbin/samba [0x889469a]
>   #28 /usr/local/samba/sbin/samba [0x8894e16]
>   #29 /usr/local/samba/sbin/samba [0x8894e84]
>   #30 /usr/local/samba/sbin/samba(event_loop_wait+0x16) [0x88914f9]
>   #31 /usr/local/samba/sbin/samba [0x80dcddf]
>   #32 /usr/local/samba/sbin/samba(main+0x38) [0x80dce3a]
>   #33 /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xc8) [0xb7b98ea8]
>   #34 /usr/local/samba/sbin/samba [0x80dbff1]
> [Thu Feb 26 15:22:00 2009 MSK, 0 
> lib/messaging/messaging.c:592:messaging_init()]
> Unable to setup messaging listener for 
> '/usr/local/samba/private/smbd.tmp/messaging/msg.0.0.102':NT_STATUS_ACCESS_DENIED 
> 10065
> [Thu Feb 26 15:22:00 2009 MSK, 2 
> smbd/process_single.c:100:single_terminate()]
> single_terminate: reason[messaging_init() failed]

This following trace is a slightly different side of the same coin:  We
can't open the schannel database when we are in that
wbc_xids_to_sids_recv call.

> [Thu Feb 26 15:50:00 2009 MSK, 2 
> libcli/cldap/cldap.c:96:cldap_socket_recv()]
> Received cldap packet of length 208 from 192.168.33.14:3747
> [Thu Feb 26 15:50:00 2009 MSK, 2 lib/socket/interface.c:96:add_interface()]
> added interface ip=192.168.33.254 nmask=0.0.0.0
> [Thu Feb 26 15:50:00 2009 MSK, 2 
> smbd/process_single.c:100:single_terminate()]
> single_terminate: reason[NT_STATUS_END_OF_FILE]
> [Thu Feb 26 15:50:00 2009 MSK, 0 ../lib/util/fault.c:62:call_backtrace()]
> BACKTRACE: 45 stack frames:
>   #0 /usr/local/samba/sbin/samba(call_backtrace+0x2b) [0x898806b]
>   #1 /usr/local/samba/sbin/samba(tdb_open_ex+0x299) [0x89a397d]
>   #2 /usr/local/samba/sbin/samba(ltdb_wrap_open+0x123) [0x87071de]
>   #3 /usr/local/samba/sbin/samba [0x870203e]
>   #4 /usr/local/samba/sbin/samba(ldb_connect_backend+0x15d) [0x8600fc1]
>   #5 /usr/local/samba/sbin/samba(ldb_connect+0xd0) [0x85f92e8]
>   #6 /usr/local/samba/sbin/samba(ldb_wrap_connect+0x263) [0x865b779]
>   #7 /usr/local/samba/sbin/samba(schannel_db_connect+0xa8) [0x865a6e8]
>   #8 /usr/local/samba/sbin/samba(schannel_fetch_session_key+0x2b) 
> [0x865b2c1]
>   #9 /usr/local/samba/sbin/samba [0x86586ad]
>   #10 /usr/local/samba/sbin/samba(gensec_update+0x3e) [0x8627ac5]
>   #11 /usr/local/samba/sbin/samba(dcesrv_auth_bind_ack+0x7b) [0x84e4c79]
>   #12 /usr/local/samba/sbin/samba [0x84e25e9]
>   #13 /usr/local/samba/sbin/samba(dcesrv_input_process+0x4e4) [0x84e3f30]
>   #14 /usr/local/samba/sbin/samba(dcesrv_input+0xc2) [0x84e4088]
>   #15 /usr/local/samba/sbin/samba [0x80e89b3]
>   #16 /usr/local/samba/sbin/samba [0x85b02bd]
>   #17 /usr/local/samba/sbin/samba [0x85b0338]
>   #18 /usr/local/samba/sbin/samba [0x889469a]
>   #19 /usr/local/samba/sbin/samba [0x8894e16]
>   #20 /usr/local/samba/sbin/samba(event_loop_once+0x16) [0x88914e1]
>   #21 /usr/local/samba/sbin/samba(composite_wait+0x40) [0x8890bc1]
>   #22 /usr/local/samba/sbin/samba(wbc_xids_to_sids_recv+0x24) [0x84c8fdd]
>   #23 /usr/local/samba/sbin/samba(pvfs_acl_inherit+0x36d) [0x84c6c6f]
>   #24 /usr/local/samba/sbin/samba [0x84b1007]
>   #25 /usr/local/samba/sbin/samba [0x84b2b9e]
>   #26 /usr/local/samba/sbin/samba(pvfs_open+0x55c) [0x84b4201]
>   #27 /usr/local/samba/sbin/samba(ntvfs_next_open+0x5e) [0x84aa2fa]
>   #28 /usr/local/samba/sbin/samba [0x84ecc33]
>   #29 /usr/local/samba/sbin/samba(ntvfs_open+0x55) [0x84a93e4]
>   #30 /usr/local/samba/sbin/samba(smbsrv_reply_ntcreate_and_X+0x3af) 
> [0x844da74]
>   #31 /usr/local/samba/sbin/samba [0x843f50d]
>   #32 /usr/local/samba/sbin/samba(smbsrv_recv_smb_request+0x594) [0x843f027]
>   #33 /usr/local/samba/sbin/samba(packet_recv+0x65b) [0x86902db]
>   #34 /usr/local/samba/sbin/samba [0x842e8eb]
>   #35 /usr/local/samba/sbin/samba [0x85b02bd]
>   #36 /usr/local/samba/sbin/samba [0x85b0338]
>   #37 /usr/local/samba/sbin/samba [0x889469a]
>   #38 /usr/local/samba/sbin/samba [0x8894e16]
>   #39 /usr/local/samba/sbin/samba [0x8894e84]
>   #40 /usr/local/samba/sbin/samba(event_loop_wait+0x16) [0x88914f9]
>   #41 /usr/local/samba/sbin/samba [0x80dcddf]
>   #42 /usr/local/samba/sbin/samba(main+0x38) [0x80dce3a]
>   #43 /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xc8) [0xb7b98ea8]
>   #44 /usr/local/samba/sbin/samba [0x80dbff1]
> [Thu Feb 26 15:50:00 2009 MSK, 2 lib/ldb_wrap.c:66:ldb_wrap_debug()]
> ldb: ltdb: tdb((null)): tdb_open_ex: could not open file 
> /usr/local/samba/private/schannel.ldb: Permission denied 66 384 10056



> [Thu Feb 26 15:50:00 2009 MSK, 1 lib/ldb_wrap.c:66:ldb_wrap_debug()]
> ldb: Unable to open tdb '/usr/local/samba/private/schannel.ldb'
> 
> [Thu Feb 26 15:50:00 2009 MSK, 1 lib/ldb_wrap.c:66:ldb_wrap_debug()]
> ldb: Failed to connect to '/usr/local/samba/private/schannel.ldb'

This last trace matches these messages.

Andrew Bartlett

-- 
Andrew Bartlett
http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Red Hat Inc.
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