Winbind using 100% CPU

[Jim McDonough]

On Thu, Apr 11, 2013 at 6:59 PM, Jeremy Allison <jra at samba.org> wrote:
> On Thu, Apr 11, 2013 at 09:58:33AM -0400, Dylan Klomparens wrote:
>> (Re-posting on this email list per Jeremy Allison's request.)
>>
>> I am trying to figure out why winbind is using 100% CPU on my file server.
>> I am using Samba version 4.0.4. Everything is fine for a few minutes when I
>> start winbind, however after a while it begins using 100% CPU. I haven't
>> been able to narrow down what triggers this CPU usage spike, but I did
>> attach the GNU debugger to find out what's going on in the process. The
>> backtrace revealed this information:
>>
>> #0  0x000000000041cf30 in _talloc_free at plt ()
>> #1  0x0000000000452320 in winbindd_reinit_after_fork ()
>> #2  0x00000000004524e6 in fork_domain_child ()
>> #3  0x0000000000453585 in wb_child_request_trigger ()
>> #4  0x000000381d2048e2 in tevent_common_loop_immediate () from
>> /lib64/libtevent.so.0
>> #5  0x00007fbed6b98e17 in run_events_poll () from /lib64/libsmbconf.so.0
>> #6  0x00007fbed6b9922e in s3_event_loop_once () from /lib64/libsmbconf.so.0
>> #7  0x000000381d204060 in _tevent_loop_once () from /lib64/libtevent.so.0
>> #8  0x000000000042049a in main ()
>>
>> Apparently it's stuck in the winbindd_reinit_after_fork (and more
>> specifically the _talloc_free function). This code resides in
>> $SOURCE_HOME\source3\winbindd\winbindd_dual.c.
>
> That looks like corrupted memory - probably a loop
> in the talloc tree.
I've got a user who sees this and we're adding the same dlinklist
element twice, creating a loop in the winbind child list.

I've got a broken wrist so responses take a while, but that's my
current hint.  On 3.6.3 and 3.6.13.

>
> Can you run under valgrind and try and reproduce ?
>
> Jeremy.



--
Jim McDonough
Samba Team
SUSE labs
jmcd at samba dot org
jmcd at themcdonoughs dot org