[lttng-dev] Double free or corruption error (fasttop)

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Mon Mar 19 16:01:53 EDT 2018 

----- On Mar 19, 2018, at 3:53 PM, Shehab Elsayed <shehabyomn at gmail.com> wrote: 

> cat /proc/sys/kernel/perf_event_paranoid ---> returns 1

> I run the program as a normal user

> The glibc version I get by running "ldd --version" is 2.17

Can you reproduce the issue after you do this as root ? 

echo "-1" > /proc/sys/kernel/perf_event_paranoid 

Based on this documentation of the Linux kernel: 

Documentation/sysctl/kernel.txt: 

perf_event_paranoid: 

Controls use of the performance events system by unprivileged 
users (without CAP_SYS_ADMIN). The default value is 2. 

-1: Allow use of (almost) all events by all users 
Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK 
>=0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN 
Disallow raw tracepoint access by users without CAP_SYS_ADMIN 
>=1: Disallow CPU event access by users without CAP_SYS_ADMIN 
>=2: Disallow kernel profiling by users without CAP_SYS_ADMIN 

Thanks, 

Mathieu 

> Shehab Y. Elsayed, MSc.
> PhD Student
> The Edwards S. Rogers Sr. Dept. of Electrical and Computer Engineering
> University of Toronto
> E-mail: [ https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11# |
> shehabyomn at gmail.com ]

> On Mon, Mar 19, 2018 at 3:31 PM, Mathieu Desnoyers < [
> mailto:mathieu.desnoyers at efficios.com | mathieu.desnoyers at efficios.com ] >
> wrote:

>> ---- On Mar 19, 2018, at 3:26 PM, Mathieu Desnoyers < [
>> mailto:mathieu.desnoyers at efficios.com | mathieu.desnoyers at efficios.com ] >
>> wrote:

>>> ----- On Mar 19, 2018, at 2:26 PM, Shehab Elsayed < [
>>> mailto:shehabyomn at gmail.com | shehabyomn at gmail.com ] > wrote:

>>>> Yes, I tried with only one of those contexts and I still ran into the same
>>>> problem.

>>> What is the setting returned by

>>> cat /proc/sys/kernel/perf_event_paranoid

>>> on your system ? And do you run your test program as root or normal user ?

>>> Please CC the mailing list on your reply.

>> I will also need to know what glibc version you have on your system.

>> Thanks,

>> Mathieu

>>> Thanks,

>>> Mathieu

>>>> Shehab Y. Elsayed, MSc.
>>>> PhD Student
>>>> The Edwards S. Rogers Sr. Dept. of Electrical and Computer Engineering
>>>> University of Toronto
>>>> E-mail: [ https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11# |
>>>> shehabyomn at gmail.com ]

>>>> On Mon, Mar 19, 2018 at 2:24 PM, Mathieu Desnoyers < [
>>>> mailto:mathieu.desnoyers at efficios.com | mathieu.desnoyers at efficios.com ] >
>>>> wrote:

>>>>> ----- On Mar 19, 2018, at 12:36 PM, Shehab Elsayed < [
>>>>> mailto:shehabyomn at gmail.com | shehabyomn at gmail.com ] > wrote:

>>>>>> Hi Mathieu,

>>>>>> Thank you very much for your reply.

>>>>>> I manually built lttng-ust from source (commit #:
>>>>>> 8a208943e21700211beee3ea64180a5a534c7d2a).

>>>>>> This is how I set up the tracing session:
>>>>>> 1- lttng create lu_ncb_8_native -o {path}
>>>>>> 2- lttng enable-event --userspace lttng_ust_pthread:pthread_mutex_lock_req
>>>>>> lttng enable-event --userspace lttng_ust_pthread:pthread_mutex_lock_acq
>>>>>> lttng enable-event --userspace lttng_ust_pthread:pthread_mutex_lock_trylock
>>>>>> lttng enable-event --userspace lttng_ust_pthread:pthread_mutex_lock_unlock
>>>>>> 3- lttng add-context -u -t procname
>>>>>> lttng add-context -u -t vpid
>>>>>> lttng add-context -u -t pthread_id
>>>>>> lttng add-context -u -t vtid
>>>>>> lttng add-context -u -t ip
>>>>>> lttng add-context -u -t perf:thread:cpu-cycles
>>>>>> lttng add-context -u -t perf:thread:cycles
>>>>>> lttng add-context -u -t perf:thread:instructions
>>>>>> 4- lttng start
>>>>>> 5- LD_PRELOAD=/usr/local/lib/liblttng-ust-pthread-wrapper.so ./lu_ncb -p8 -n8096
>>>>>> -b32
>>>>>> 6- lttng stop
>>>>>> 7- lttng destroy

>>>>> Can you reproduce if you remove the following contexts ?

>>>>> lttng add-context -u -t perf:thread:cpu-cycles
>>>>> lttng add-context -u -t perf:thread:cycles
>>>>> lttng add-context -u -t perf:thread:instructions

>>>>> And if you only keep a single of those contexts ?

>>>>> Thanks,

>>>>> Mathieu

>>>>>> Shehab Y. Elsayed, MSc.
>>>>>> PhD Student
>>>>>> The Edwards S. Rogers Sr. Dept. of Electrical and Computer Engineering
>>>>>> University of Toronto
>>>>>> E-mail: [ https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11# |
>>>>>> shehabyomn at gmail.com ]

>>>>>> On Mon, Mar 19, 2018 at 12:21 PM, Mathieu Desnoyers < [
>>>>>> mailto:mathieu.desnoyers at efficios.com | mathieu.desnoyers at efficios.com ] >
>>>>>> wrote:

>>>>>>> ----- On Mar 16, 2018, at 5:37 PM, Shehab Elsayed < [
>>>>>>> mailto:shehabyomn at gmail.com | shehabyomn at gmail.com ] > wrote:

>>>>>>>> Hello All,

>>>>>>>> I am trying to instrument a pthread application using the provided pthread
>>>>>>>> wrapper, but I sometimes run into a "Double free or corruption error ( fasttop
>>>>>>>> )" error.

>>>>>>> Please provide more information about the version of lttng-ust you are using,
>>>>>>> and how you setup
>>>>>>> your tracing session.

>>>>>>> Thanks,

>>>>>>> Mathieu

>>>>>>>> Here is a description of what I have tried and noticed:
>>>>>>>> 1- The problem isn't consistent. It sometimes happen and sometimes works as
>>>>>>>> expected.
>>>>>>>> 2- From my experiments, the problem happens (more frequently at least) when
>>>>>>>> adding performance counter contexts (I tried cycles, cpu _cycles and
>>>>>>>> instructions).
>>>>>>>> 3- I am testing using lu _ ncb from splash3 benchmark suite after setting LD _
>>>>>>>> PRELOAD to use the pthread wrapper as described in the LTTng documents.
>>>>>>>> 4- Here is the backtrace printed after exiting:
>>>>>>>> ======= Backtrace : =========
>>>>>>>> /lib64/ libc .so.6([Thread 0x7ffff5611700 ( LWP 97229) exited]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng
>>>>>>>> _destroy_context+0x35)[0x7ffff7471575]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng
>>>>>>>> _session_destroy+0x21c)[0x7ffff747363c]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0(+0x1e906)[0x7ffff746d906]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng _ ust _ objd _ unref
>>>>>>>> +0x9f)[0x7ffff746dccf]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng _ ust _ objd _ unref
>>>>>>>> +0x9f)[0x7ffff746dccf]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng _ ust _ objd _ unref
>>>>>>>> +0x9f)[0x7ffff746dccf]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng _ ust _ abi
>>>>>>>> _exit+0x68)[0x7ffff746ead8]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0(+0x191d3)[0x7ffff74681d3]
>>>>>>>> / usr /local/lib/ liblttng - ust .so.0( lttng _ ust _exit+0x67)[0x7ffff745ed57]
>>>>>>>> /lib64/ ld - linux -x86-64.so.2(+0xf85a)[0x7ffff7dec85a]
>>>>>>>> /lib64/ libc .so.6(+0x38a49)[0x7ffff6ca6a49]
>>>>>>>> /lib64/ libc .so.6(+0x38a95)[0x7ffff6ca6a95]
>>>>>>>> / aenao -99/elsayed9/ LTTng /data/scripts/ tmp / lu _ ncb [0x401b51]
>>>>>>>> /lib64/ libc .so.6(__ libc _start_main+0xf5)[0x7ffff6c8fb35]
>>>>>>>> / aenao -99/elsayed9/ LTTng /data/scripts/ tmp / lu _ ncb [0x401c44]
>>>>>>>> 5- Also, this is a backtrace I obtained from gdb :
>>>>>>>> #0 0x00007ffff6eac1d7 in raise () from /lib64/ libc .so.6
>>>>>>>> #1 0x00007ffff6ead8c8 in abort () from /lib64/ libc .so.6
>>>>>>>> #2 0x00007ffff6eebf07 in __ libc _message () from /lib64/ libc .so.6
>>>>>>>> #3 0x00007ffff6ef3503 in _int_free () from /lib64/ libc .so.6
>>>>>>>> #4 0x00007ffff768ad25 in lttng _destroy_ perf _counter_field (
>>>>>>>> field=<optimized out>) at lttng -context- perf -counters.c:418
>>>>>>>> #5 0x00007ffff767a575 in lttng _destroy_context (
>>>>>>>> ctx =0x7ffff0011090) at lttng -context.c:278
>>>>>>>> #6 0x00007ffff767c63c in _ lttng _channel_ unmap (
>>>>>>>> lttng _ chan =0x7ffff0010f40) at lttng -events.c:172
>>>>>>>> #7 lttng _session_destroy (session=0x7ffff0000900)
>>>>>>>> at lttng -events.c:247
>>>>>>>> #8 0x00007ffff7676906 in lttng _release_session (
>>>>>>>> objd =<optimized out>) at lttng - ust - abi .c:601
>>>>>>>> #9 0x00007ffff7676ccf in lttng _ ust _ objd _ unref (id=1,
>>>>>>>> is_owner=<optimized out>) at lttng - ust - abi .c:216
>>>>>>>> #10 0x00007ffff7676ccf in lttng _ ust _ objd _ unref (id=2,
>>>>>>>> is_owner=<optimized out>) at lttng - ust - abi .c:216
>>>>>>>> #11 0x00007ffff7676ccf in lttng _ ust _ objd _ unref (id=id at entry=18,
>>>>>>>> is_owner=is_owner at entry=1) at lttng - ust - abi .c:216
>>>>>>>> #12 0x00007ffff7677ad8 in objd _table_destroy ()
>>>>>>>> at lttng - ust - abi .c:235
>>>>>>>> #13 lttng _ ust _ abi _exit () at lttng - ust - abi .c:1002
>>>>>>>> #14 0x00007ffff76711d3 in lttng _ ust _cleanup (exiting=1)
>>>>>>>> at lttng - ust -comm.c:1807
>>>>>>>> #15 0x00007ffff7667d57 in lttng _ ust _exit ()
>>>>>>>> at lttng - ust -comm.c:1874
>>>>>>>> #16 0x00007ffff7dec85a in _ dl _ fini ()
>>>>>>>> from /lib64/ ld - linux -x86-64.so.2
>>>>>>>> #17 0x00007ffff6eafa49 in __run_exit_handlers ()
>>>>>>>> from /lib64/ libc .so.6
>>>>>>>> #18 0x00007ffff6eafa95 in exit () from /lib64/ libc .so.6
>>>>>>>> #19 0x0000000000401b51 in main ( argc =<optimized out>,
>>>>>>>> argv =<optimized out>) at lu .c:368

>>>>>>>> Any ideas, why this happens and how to fix it?

>>>>>>>> Thanks,
>>>>>>>> Shehab

>>>>>>>> _______________________________________________
>>>>>>>> lttng-dev mailing list
>>>>>>>> [ mailto:lttng-dev at lists.lttng.org | lttng-dev at lists.lttng.org ]
>>>>>>>> [ https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev |
>>>>>>>> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev ]

>>>>>>> --
>>>>>>> Mathieu Desnoyers
>>>>>>> EfficiOS Inc.
>>>>>>> [ http://www.efficios.com/ | http://www.efficios.com ]

>>>>> --
>>>>> Mathieu Desnoyers
>>>>> EfficiOS Inc.
>>>>> [ http://www.efficios.com/ | http://www.efficios.com ]

>>> --
>>> Mathieu Desnoyers
>>> EfficiOS Inc.
>>> [ http://www.efficios.com/ | http://www.efficios.com ]

>> --
>> Mathieu Desnoyers
>> EfficiOS Inc.
>> [ http://www.efficios.com/ | http://www.efficios.com ]

-- 
Mathieu Desnoyers 
EfficiOS Inc. 
http://www.efficios.com 
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