Re: [Discuss-gnuradio] segmentation fault in qa_constellation_receiver_test

[Kelly Boswell]

I'm encountering the same problem on maint.  And I did remember to rebuild. I removed the build directory, recreated it, and started over with cmake just to be sure.  It's the same stack trace.

On Fri, Feb 21, 2014 at 7:54 PM, West, Nathan <address@hidden> wrote:

If you just want to get back to a system that passes QA you should
just be able to build off of maint.

On Fri, Feb 21, 2014 at 6:05 PM, Kelly Boswell <address@hidden> wrote:
> I removed the implementation of volk_malloc that uses posix_menacing by
> commenting everything from the #if to #else and the final #endif but the
> segmentation fault remains. I noticed it's being called in a few other files
> as well. Do I need to remove those, too? Thanks in advance.
>
> On Feb 21, 2014 10:21 AM, "Kelly Boswell" <address@hidden> wrote:
>>
>> Thank you, Tom. I'll try that after I'm off of work tonight. And thank you
>> for the great ideas, Nathan.
>>
>> On Fri, Feb 21, 2014 at 2:39 AM, West, Nathan
>> <address@hidden> wrote:
>> > On Thu, Feb 20, 2014 at 11:25 PM, Kelly Boswell <address@hidden>
>> > wrote:
>> >> After the make test failed for this module, I decided to poke around to
>> >> see
>> >> if there is an easy fix. I made a script that simply executes the test
>> >> over
>> >> and over until it seg faults and exits after the core file is created.
>> >>
>> >> address@hidden:~/src/gnuradio/build/gr-digital/python/digital$
>> >> ./runtests.sh
>> >> Using Volk machine: avx_64_mmx
>> >> Segmentation fault (core dumped)
>> >>
>> >> address@hidden:~/src/gnuradio/build/gr-digital/python/digital$ gdb
>> >> /usr/bin/python2.7 core
>> >> (gdb) bt
>> >> (gdb) bt
>> >> #0  0x00007fe8f627fb17 in volk_32fc_32f_dot_prod_32fc_a_avx ()
>> >>    from /home/kelly/src/gnuradio/build/volk/lib/libvolk.so.0.0.0
>> >> #1  0x00007fe8f52dd25f in
>> >> gr::filter::kernel::fir_filter_ccf::filter(std::complex<float> const*)
>> >> ()
>> >>    from
>> >>
>> >> /home/kelly/src/gnuradio/build/gr-filter/lib/libgnuradio-filter-3.8git.so.0.0.0
>> >> #2  0x00007fe8f143c45b in
>> >> gr::digital::pfb_clock_sync_ccf_impl::general_work(int,
>> >> std::vector<int,
>> >> std::allocator<int> >&, std::vector<void const*, std::allocator<void
>> >> const*>
>> >>>&, std::vector<void*, std::allocator<void*> >&) ()
>> >>    from
>> >>
>> >> /home/kelly/src/gnuradio/build/gr-digital/lib/libgnuradio-digital-3.8git.so.0.0.0
>> >> #3  0x00007fe8f653809e in gr::block_executor::run_one_iteration() ()
>> >>    from
>> >>
>> >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0
>> >> #4  0x00007fe8f6573622 in
>> >> gr::tpb_thread_body::tpb_thread_body(boost::shared_ptr<gr::block>, int)
>> >> ()
>> >>    from
>> >>
>> >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0
>> >> #5  0x00007fe8f6565ea1 in
>> >>
>> >> boost::detail::function::void_function_obj_invoker0<gr::thread::thread_body_wrapper<gr::tpb_container>,
>> >> void>::invoke(boost::detail::function::function_buffer&) ()
>> >>    from
>> >>
>> >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0
>> >> ---Type <return> to continue, or q <return> to quit---
>> >> #6  0x00007fe8f6526610 in
>> >> boost::detail::thread_data<boost::function0<void>
>> >>>::run() ()
>> >>    from
>> >>
>> >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0
>> >> #7  0x00007fe8f9adc94a in ?? ()
>> >>    from /usr/lib/x86_64-linux-gnu/libboost_thread.so.1.53.0
>> >> #8  0x00007fe8fc8a3f6e in start_thread (arg=0x7fe8e2ffd700)
>> >>     at pthread_create.c:311
>> >> #9  0x00007fe8fc5ce9cd in clone ()
>> >>     at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
>> >>
>> >> Of course, I had to recompile it with debugging info to glean anything
>> >> useful from the stack trace.  So, I did that and I traced the bug to
>> >> this
>> >> line:
>> >>
>> >> c0Val = _mm256_mul_ps(a0Val, b0Val);
>> >>
>> >> I can't dump the values in a0Val or b0Val, though, because they're
>> >> intermediate values that are optimized away by the optimized kernel
>> >> code.  I
>> >> tried stepping through the assembler instructions but I'm not familiar
>> >> with
>> >> the various sse and avx extensions. Heck, I'm not even familiar with
>> >> the
>> >> x86_64 instruction set.  So I have a huge learning curve ahead of me,
>> >> there.
>> >> Is it possible to just dump the values in these __m256 data types to a
>> >> file
>> >> so I can debug it that way?  If that's not easy to do, then I'm willing
>> >> to
>> >> learn what I have to about the instruction set so I can debug this
>> >> thing.
>> >> But I would sure appreciate some help if anyone has some advice to
>> >> offer.
>> >>
>> >> Software version:
>> >> I rebased to the latest version of the next branch last night before I
>> >> went
>> >> to bed at around 1:30 am CDT.
>> >>
>> >> Operating System:
>> >> address@hidden:~/src/gnuradio/volk/kernels/volk$ uname -a
>> >> Linux octs2 3.11.0-17-generic #31-Ubuntu SMP Mon Feb 3 21:52:43 UTC
>> >> 2014
>> >> x86_64 x86_64 x86_64 GNU/Linux
>> >> It's Ubuntu 13.10
>> >>
>> >> Hardware: ASUS X750J
>> >> Intel Quad Core i7 4700HQ 2.4GHz
>> >>
>> >> cpuinfo:
>> >> processor    : 7
>> >> vendor_id    : GenuineIntel
>> >> cpu family    : 6
>> >> model        : 60
>> >> model name    : Intel(R) Core(TM) i7-4700HQ CPU @ 2.40GHz
>> >> stepping    : 3
>> >> microcode    : 0x8
>> >> cpu MHz        : 2401.000
>> >> cache size    : 6144 KB
>> >> physical id    : 0
>> >> siblings    : 8
>> >> core id        : 3
>> >> cpu cores    : 4
>> >> apicid        : 7
>> >> initial apicid    : 7
>> >> fpu        : yes
>> >> fpu_exception    : yes
>> >> cpuid level    : 13
>> >> wp        : yes
>> >> flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
>> >> cmov
>> >> pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx
>> >> pdpe1gb
>> >> rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology
>> >> nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx
>> >> est
>> >> tm2 ssse3 fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt
>> >> tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat epb
>> >> xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase
>> >> tsc_adjust bmi1 avx2 smep bmi2 erms invpcid
>> >> bogomips    : 4789.27
>> >> clflush size    : 64
>> >> cache_alignment    : 64
>> >> address sizes    : 39 bits physical, 48 bits virtual
>> >> power management:
>> >>
>> >
>> >
>> > Hi Kelly,
>> >
>> > First, this is great debugging, thanks for getting so much info and
>> > trying to go for a fix on your own.
>> >
>> > On to the good stuff. I was able to reproduce this on my i7-4700MQ.
>> > Here's some additional info for the logs:
>> >
>> > * constellation_receiver is a hier block with a fir_filter_ccf inside
>> > that is calling the volk avx dot product.
>> > * The avx dot product proto-kernel passes VOLK QA
>> > * The qa_fir_filter.py is testing a fir_filter_ccf that passes its QA.
>> > * Just for kicks, I forced VOLK to use the generic kernel and I still
>> > see the segfault.
>> >
>> > A couple of things I'd like to try (and please feel free to give these a
>> > try):
>> > * Go back to a commit just before fir_filter.cc started using
>> > volk_malloc and volk_free.  (or for bonus points go back to some point
>> > in time when this test always passes and do a git bisect)
>> > * fiddle with parameters of the test, data length, number of taps in
>> > filter, etc.
>> > * Doubtful this would change, but test on different processors. It
>> > would be pretty wild if there was something off in the 4700 line, but
>> > the fact that the generic proto-kernel had the same result and nobody
>> > else has reported this yet is suspicious. My guess is GCC is actually
>> > emitting *very* similar code for the generic and avx dot product
>> > proto-kernels.
>> >
>> > Nathan
>>
>>
>> I was having similar issues this week with some AVX boxes. It looks
>> like it's a problem using posix_memalign (which is called by
>> volk_malloc if posix_memalign is available). Removing the use of
>> posix_memalign solves my problem. I'll work with Nathan off-list to
>> see about fixing this, possibly by removing the use of that version of
>> malloc.
>>
>> Tom
>
>

> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>