[lttng-dev] Double free or corruption error (fasttop)
Shehab Elsayed
shehabyomn at gmail.com
Wed Mar 21 19:55:48 EDT 2018
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_
>> 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 ?
>>
>> 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_
>>>>> 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: 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)[
>>>>>> 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
>>>>>> 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
>
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