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

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Tue Mar 20 12:07:44 EDT 2018 

----- On Mar 19, 2018, at 4:21 PM, Shehab Elsayed <shehabyomn at gmail.com> wrote: 

> I did "echo "-1" > /proc/sys/kernel/perf_event_paranoid " and made sure the
> value was actually written by "cat /proc/sys/kernel/perf_event_paranoid"

> It executed normally 2 times but then got the same error.

Can you provide the output when reproducing the issue with the 
LTTNG_UST_DEBUG=1 environment variable set when starting 
your test program ? 

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 4:01 PM, Mathieu Desnoyers < [
> mailto:mathieu.desnoyers at efficios.com | mathieu.desnoyers at efficios.com ] >
> wrote:

>> ----- On Mar 19, 2018, at 3:53 PM, Shehab Elsayed < [
>> mailto:shehabyomn at gmail.com | 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/ | http://www.efficios.com ]

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