[Samba] Problem with heaps of sleeping smb processes due to panic action

[Andrew Bartlett]

On Tue, 2012-08-14 at 15:21 +0200, Dieter Modig wrote:
> Hi! 
> 
> We're running Samba4 (Version 4.0.0beta4) and are experiencing problems with smb_panic actions which result in loads of sleep processes in the end taking down the entire machine. This problem did not exist in prior builds for us (upgraded from alpha17 to beta3 and then beta4). Are there any specific log extracts I can supply that can help someone pinpoint the problem? log.smbd seems to indicate the following: 
> 
> [2012/07/06 13:52:36.425367, 0] ../source3/lib/util.c:974(log_stack_trace) 
> BACKTRACE: 27 stack frames: 
> #0 /usr/local/samba/lib/libsmbconf.so.0(log_stack_trace+0x1f) [0x7f37c35011df] 
> #1 /usr/local/samba/lib/libsmbconf.so.0(smb_panic_s3+0x6d) [0x7f37c350105d] 
> #2 /usr/local/samba/lib/libsamba-util.so.0(smb_panic+0x28) [0x7f37c5323aee] 
> #3 /usr/local/samba/lib/private/libsmbd_base.so(+0x129b89) [0x7f37c4ac6b89] 
> #4 /usr/local/samba/lib/private/libsmbd_base.so(+0x129ea9) [0x7f37c4ac6ea9] 
> #5 /usr/local/samba/lib/private/libsmbd_base.so(+0x12c769) [0x7f37c4ac9769] 
> #6 /usr/local/samba/lib/private/libsmbd_base.so(+0x130045) [0x7f37c4acd045] 
> #7 /usr/local/samba/lib/private/libsmbd_base.so(create_file_default+0x2f8) [0x7f37c4acdb7f] 
> #8 /usr/local/samba/lib/private/libsmbd_base.so(+0x23f813) [0x7f37c4bdc813] 
> #9 /usr/local/samba/lib/private/libsmbd_base.so(smb_vfs_call_create_file+0xcb) [0x7f37c4ad8fc8] 
> #10 /usr/local/samba/lib/private/libsmbd_base.so(+0x1771b2) [0x7f37c4b141b2] 
> #11 /usr/local/samba/lib/private/libsmbd_base.so(smbd_smb2_request_process_create+0x7ac) [0x7f37c4b1224c] 
> #12 /usr/local/samba/lib/private/libsmbd_base.so(smbd_smb2_request_dispatch+0x6fe) [0x7f37c4b0a42d] 
> #13 /usr/local/samba/lib/private/libsmbd_base.so(+0x1781ce) [0x7f37c4b151ce] 
> #14 /usr/local/samba/lib/private/libtevent.so.0(tevent_common_loop_immediate+0x1f9) [0x7f37c376a090] 
> #15 /usr/local/samba/lib/libsmbconf.so.0(run_events_poll+0x57) [0x7f37c351d23f] 
> #16 /usr/local/samba/lib/libsmbconf.so.0(+0x44ac2) [0x7f37c351dac2] 
> #17 /usr/local/samba/lib/private/libtevent.so.0(_tevent_loop_once+0xe8) [0x7f37c376918f] 
> #18 /usr/local/samba/lib/private/libsmbd_base.so(smbd_process+0x10ed) [0x7f37c4af4569] 
> #19 /usr/local/samba/sbin/smbd() [0x409c48] 
> #20 /usr/local/samba/lib/libsmbconf.so.0(run_events_poll+0x71a) [0x7f37c351d902] 
> #21 /usr/local/samba/lib/libsmbconf.so.0(+0x44ba2) [0x7f37c351dba2] 
> #22 /usr/local/samba/lib/private/libtevent.so.0(_tevent_loop_once+0xe8) [0x7f37c376918f] 
> #23 /usr/local/samba/sbin/smbd() [0x40a838] 
> #24 /usr/local/samba/sbin/smbd(main+0x14b9) [0x40be42] 
> #25 /lib/libc.so.6(__libc_start_main+0xfd) [0x7f37c1e02c8d] 
> #26 /usr/local/samba/sbin/smbd() [0x405969] 
> [2012/07/06 13:52:36.430994, 0] ../source3/lib/util.c:875(smb_panic_s3) 
> 
> but I'm honestly not good enough to dissect the problem. 

In developer mode, the default panic action is to run 'sleep' so you can
attach with a debugger (see testparm -v output). 

To instead produce a stack trace that we can use, get 'gdb_backtrace'
from selftest/gdb_backtrace and set in your smb.conf:

panic action = /path/to/gdb_backtrace %d

I've CC'ed metze, one of the key developers working on the smbd file
server to see if he wants to persue this with you further on beta4. 

Otherwise, please update to current master as this is a fast-moving area
that may have already been fixed.

Andrew Bartlett

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