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

Shehab Elsayed shehabyomn at gmail.com
Wed Mar 21 20:01:30 EDT 2018 

Just to clarify more what I meant by custom events; I have new tracepoints
added in the source code of the benchmark. However, I don't enable the
corresponding events when I do the actual tracing.

This is the sequence followed in building the benchmark:
gcc-7.2 -c -O2 -pthread -D_XOPEN_SOURCE=500 -D_POSIX_C_SOURCE=200112
-std=c11 -g -fno-strict-aliasing -DLTTNG_INST lu.c
gcc-7.2 -O2 -pthread -D_XOPEN_SOURCE=500 -D_POSIX_C_SOURCE=200112 -std=c11
-g -fno-strict-aliasing -DLTTNG_INST -o LU_NCB lu.o
../../instrumentation/lttng_tp/tp.o -lm -llttng-ust -ldl

LTTNG_INST is just a preprocessor flag I have and tp.o is my custom
tracepoints

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

On Wed, Mar 21, 2018 at 7:55 PM, Shehab Elsayed <shehabyomn at gmail.com>
wrote:

> Still running into same problem. I attached the debug trace I got after
> applying the 2 patches.
>
> The benchmark I am running also includes some custom created tracepoints.
> I am not adding the events being traced in the files I have provided. Do
> you think this might be causing a problem when I have tracpoints from 2
> different packages?
>
> Shehab Y. Elsayed, MSc.
> PhD Student
> The Edwards S. Rogers Sr. Dept. of Electrical and Computer Engineering
> University of Toronto
> E-mail: shehabyomn at gmail.com
> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#>
>
> On Wed, Mar 21, 2018 at 4:22 PM, Mathieu Desnoyers <
> mathieu.desnoyers at efficios.com> wrote:
>
>> ----- On Mar 21, 2018, at 1:55 PM, Shehab Elsayed <shehabyomn at gmail.com>
>> wrote:
>>
>> I am so sorry for the late replies.
>>
>> I have tried the first patch you sent and the problem still happens
>> (although seemingly less frequently especially with debugging enabled!!!!).
>> I have attached the output I got from one of the erroneous runs.
>>
>> I will try the updated patch and let you know how it goes.
>>
>> Also, I am not sure if these points make any difference:
>> 1- The error actually happens at the end of the application. It actually
>> finishes execution, but then something goes wrong.
>> 2- I run into this problem only for some of the benchmarks (or at least
>> the problems happens much less frequently for others that I didn't run into
>> it, not yet)
>>
>> Thanks you very much, and sorry again for the late replies.
>>
>>
>> No worries! Looking through your log, I notice that pthread set cancel
>> state has problems when
>> called from application threads. We do not restore the original thread's
>> cancel state. Can you try
>> with the attached patch applied on top of the previous one ?
>>
>> Thanks,
>>
>> Mathieu
>>
>>
>>
>>
>> Shehab Y. Elsayed, MSc.
>> PhD Student
>> The Edwards S. Rogers Sr. Dept. of Electrical and Computer Engineering
>> University of Toronto
>> E-mail: shehabyomn at gmail.com
>> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#>
>>
>> On Wed, Mar 21, 2018 at 1:27 PM, Mathieu Desnoyers <
>> mathieu.desnoyers at efficios.com> wrote:
>>
>>> ----- On Mar 20, 2018, at 5:42 PM, Mathieu Desnoyers <
>>> mathieu.desnoyers at efficios.com> wrote:
>>>
>>> ----- On Mar 20, 2018, at 4:58 PM, Mathieu Desnoyers <
>>> mathieu.desnoyers at efficios.com> wrote:
>>>
>>> ----- On Mar 20, 2018, at 12:07 PM, Mathieu Desnoyers <
>>> mathieu.desnoyers at efficios.com> wrote:
>>>
>>>
>>> ----- 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_pa
>>> ranoid"
>>>
>>> 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 ?
>>>
>>> I just noticed something that might explain what goes wrong here:
>>>
>>> lttng-context-perf-counters.c: add_thread_field() grabs the ust_lock().
>>> Pthread mutex
>>> in your case is instrumented with the pthread wrapper. This
>>> "add_thread_field" is invoked
>>> the first time the perf counter is hit by each given thread. When this
>>> happens, the
>>> instrumented pthread mutex will try to call into the instrumentation
>>> tracepoint again,
>>> which will call add_thread_field() (again), and so on until we reach the
>>> libringbuffer
>>> "lib_ring_buffer_nesting" threshold of 4 calls deep.
>>>
>>> I suspect this situation where we recursively call add_thread_field is
>>> unexpected,
>>> which may trigger your double-free here.
>>>
>>> Will investigate more.
>>>
>>> Can you try with the attached patch applied ?
>>>
>>> Here is an updated v2 of the patch which tests the notrace tls counter
>>> sooner (before evaluating
>>> filter). Please let me know how it goes.
>>>
>>> Thanks,
>>>
>>> Mathieu
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Mathieu
>>>
>>>
>>>
>>>
>>>
>>> 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: shehabyomn at gmail.com
>>> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#>
>>>
>>> On Mon, Mar 19, 2018 at 4:01 PM, Mathieu Desnoyers <
>>> mathieu.desnoyers at efficios.com> wrote:
>>>
>>>>
>>>>
>>>> ----- 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: shehabyomn at gmail.com
>>>> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#>
>>>>
>>>> On Mon, Mar 19, 2018 at 3:31 PM, Mathieu Desnoyers <
>>>> mathieu.desnoyers at efficios.com> wrote:
>>>>
>>>>> ---- On Mar 19, 2018, at 3:26 PM, Mathieu Desnoyers <
>>>>> mathieu.desnoyers at efficios.com> wrote:
>>>>>
>>>>> ----- On Mar 19, 2018, at 2:26 PM, Shehab Elsayed <
>>>>> 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: shehabyomn at gmail.com
>>>>> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#>
>>>>>
>>>>> On Mon, Mar 19, 2018 at 2:24 PM, Mathieu Desnoyers <
>>>>> mathieu.desnoyers at efficios.com> wrote:
>>>>>
>>>>>> ----- On Mar 19, 2018, at 12:36 PM, Shehab Elsayed <
>>>>>> 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_mute
>>>>>> x_lock_req
>>>>>>     lttng enable-event --userspace lttng_ust_pthread:pthread_mute
>>>>>> x_lock_acq
>>>>>>     lttng enable-event --userspace lttng_ust_pthread:pthread_mute
>>>>>> x_lock_trylock
>>>>>>     lttng enable-event --userspace lttng_ust_pthread:pthread_mute
>>>>>> x_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: shehabyomn at gmail.com
>>>>>> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#>
>>>>>>
>>>>>> On Mon, Mar 19, 2018 at 12:21 PM, Mathieu Desnoyers <
>>>>>> mathieu.desnoyers at efficios.com> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ----- On Mar 16, 2018, at 5:37 PM, Shehab Elsayed <
>>>>>>> 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)[0x
>>>>>>> 7ffff746ead8]
>>>>>>> /usr/local/lib/liblttng-ust.so.0(+0x191d3)[0x7ffff74681d3]
>>>>>>> /usr/local/lib/liblttng-ust.so.0(lttng_ust_exit+0x67)[0x7fff
>>>>>>> f745ed57]
>>>>>>> /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
>>>>>>> lttng-dev at lists.lttng.org
>>>>>>> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Mathieu Desnoyers
>>>>>>> EfficiOS Inc.
>>>>>>> http://www.efficios.com
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Mathieu Desnoyers
>>>>>> EfficiOS Inc.
>>>>>> http://www.efficios.com
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Mathieu Desnoyers
>>>>> EfficiOS Inc.
>>>>> http://www.efficios.com
>>>>>
>>>>>
>>>>> --
>>>>> Mathieu Desnoyers
>>>>> EfficiOS Inc.
>>>>> http://www.efficios.com
>>>>>
>>>>
>>>>
>>>> --
>>>> Mathieu Desnoyers
>>>> EfficiOS Inc.
>>>> http://www.efficios.com
>>>>
>>>
>>>
>>> --
>>> Mathieu Desnoyers
>>> EfficiOS Inc.
>>> http://www.efficios.com
>>>
>>>
>>> --
>>> Mathieu Desnoyers
>>> EfficiOS Inc.
>>> http://www.efficios.com
>>>
>>>
>>> --
>>> Mathieu Desnoyers
>>> EfficiOS Inc.
>>> http://www.efficios.com
>>>
>>>
>>> --
>>> Mathieu Desnoyers
>>> EfficiOS Inc.
>>> http://www.efficios.com
>>>
>>
>>
>> --
>> Mathieu Desnoyers
>> EfficiOS Inc.
>> http://www.efficios.com
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.lttng.org/pipermail/lttng-dev/attachments/20180321/45824c96/attachment-0001.html>

More information about the lttng-dev mailing list