[erlang-questions] Segfault in NIF call

Greg Burd <>
Tue Apr 30 15:13:30 CEST 2013


Are you trying to build a NIF where the function is run on a
non-Erlang scheduler thread (async, via some thread pool)?  If so,
here's a method for doing it.

https://gist.github.com/gburd/4121795

It took a while to get this just right, reuse and enjoy.  I'll update
the nifwait (https://github.com/basho/nifwait) repo with example code.
 The best example of how to use it is in the wterl
(https://github.com/basho-labs/wterl) repo.

-greg

@gregburd | Basho Technologies | Riak | http://basho.com | @basho


On Mon, Apr 29, 2013 at 2:57 PM, Fredrik Linder <> wrote:
> Found one error (yay!) -- enif_open_resource_type should have NULL as the
> module argument (missed this one in the docs)
>
> Running with cerl does not generate a segfault, nor any (extra) printouts
> Running with erl still generate segfault
>
> Now I get either of the following (using erl), does it reveal what my error
> is?
>
>> USE_GDB=1 rebar eunit
> [cut]
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x2aaaad6c0700 (LWP 6384)]
> 0x000000000052b28a in process_main () at
> x86_64-unknown-linux-gnu/opt/smp/beam_hot.h:979
> 979    MoveDeallocateReturn(xb(tmp_packed1&BEAM_LOOSE_MASK), r(0),
> Qb((tmp_packed1>>BEAM_LOOSE_SHIFT)));
> (gdb) backtrace
> #0  0x000000000052b28a in process_main () at
> x86_64-unknown-linux-gnu/opt/smp/beam_hot.h:979
> #1  0x0000000000491463 in sched_thread_func (vesdp=0x2aaaac343ac0) at
> beam/erl_process.c:5632
> #2  0x0000000000590440 in thr_wrapper (vtwd=0x7fffffffd850) at
> pthread/ethread.c:106
> #3  0x00002aaaab3ffe9a in start_thread (arg=0x2aaaad6c0700) at
> pthread_create.c:308
> #4  0x00002aaaab911cbd in clone () at
> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
> #5  0x0000000000000000 in ?? ()
>
> or
>
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x2aaaad6c0700 (LWP 6914)]
> unlink_free_block (allctr=0x85e5c0, block=0x0, flags=0) at
> beam/erl_goodfit_alloc.c:458
> 458    Uint sz = MBC_FBLK_SZ(&blk->block_head);
> (gdb) backtrace
> #0  unlink_free_block (allctr=0x85e5c0, block=0x0, flags=0) at
> beam/erl_goodfit_alloc.c:458
> #1  0x0000000000444ee1 in get_free_block (allctr=0x85e5c0, size=<optimized
> out>, cand_blk=0x0, cand_size=0, flags=0) at beam/erl_goodfit_alloc.c:426
> #2  0x000000000043b6da in mbc_alloc_block (alcu_flgsp=<synthetic pointer>,
> blk_szp=<synthetic pointer>, size=<optimized out>, allctr=0x85e5c0) at
> beam/erl_alloc_util.c:1309
> #3  mbc_alloc (allctr=0x85e5c0, size=<optimized out>) at
> beam/erl_alloc_util.c:1451
> #4  0x0000000000440d7b in do_erts_alcu_alloc (size=32, extra=0x85e5c0,
> type=148) at beam/erl_alloc_util.c:3530
> #5  erts_alcu_alloc_thr_pref (type=148, extra=<optimized out>,
> size=<optimized out>) at beam/erl_alloc_util.c:3607
> #6  0x0000000000490595 in erts_alloc (size=32, type=18967) at
> beam/erl_alloc.h:208
> #7  new_message_buffer (size=0) at beam/erl_message.c:72
> #8  erts_alloc_message_heap_state (statep=0x2aaaad6bfc4c,
> receiver_locks=0x2aaaad6bfcb0, receiver=0x2aaaac9c1db8, ohpp=<synthetic
> pointer>, bpp=<synthetic pointer>, size=0) at beam/global.h:1017
> #9  erts_send_message (sender=0x2aaaac9c2470, receiver=0x2aaaac9c1db8,
> receiver_locks=0x2aaaad6bfcb0, message=564171, flags=<optimized out>) at
> beam/erl_message.c:1039
> #10 0x0000000000476350 in do_send (p=0x2aaaac9c2470, to=793099, msg=564171,
> suspend=1, refp=<optimized out>) at beam/bif.c:2025
> #11 0x0000000000476bf0 in erl_send (p=0x2aaaac9c2470, to=793099, msg=564171)
> at beam/bif.c:2138
> #12 0x000000000052d1d8 in process_main () at beam/beam_emu.c:2558
> #13 0x0000000000491463 in sched_thread_func (vesdp=0x2aaaac343ac0) at
> beam/erl_process.c:5632
> #14 0x0000000000590440 in thr_wrapper (vtwd=0x7fffffffd850) at
> pthread/ethread.c:106
> #15 0x00002aaaab3ffe9a in start_thread (arg=0x2aaaad6c0700) at
> pthread_create.c:308
> #16 0x00002aaaab911cbd in clone () at
> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
> #17 0x0000000000000000 in ?? ()
>
>
> /Fredrik
>
>
>
>
>
>
> On Mon, Apr 29, 2013 at 2:58 AM, Sverker Eriksson
> <> wrote:
>>
>> Looks like some sort of memory corruption.
>>
>> Run on debug emulator and hope for a better (earlier) crash.
>>
>> # cd $ERL_TOP/erts/emulator
>> # make TYPE=debug smp plain
>> # $ERL_TOP/bin/cerl -debug
>>
>> /Sverker, Erlang/OTP Ericsson
>>
>>  wrote:
>>>
>>> Hello folks,
>>>
>>> I'm having difficulties locating the cause of a segfault I'm getting when
>>> running tests with a NIF implementation I have.
>>>
>>> Anything that would shed light on what's wrong is appreciated.
>>>
>>> The backtrace does not seem to have anything to do with my NIF. The
>>> NIF:ed function is called from a few different processes, and it forwards
>>> the call to a worker thread which sends a message back to the caller
>>> process.
>>>
>>>
>>>>
>>>> strings -a
>>>
>>>
>>> ../../otp/R16B/pre-5.10.1-mz-0.2/lib/erlang/erts-5.10.1/bin/beam.smp|fgrep
>>> GCC|sort -u
>>> GCC: (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
>>>
>>>
>>>>
>>>> USE_GDB=1 rebar eunit
>>>>
>>>
>>> [cut]
>>> Program received signal SIGSEGV, Segmentation fault.
>>> [Switching to Thread 0x2aaaef381700 (LWP 19162)]
>>> unlink_free_block (allctr=0x85f240, block=0x0, flags=0) at
>>> beam/erl_goodfit_alloc.c:458
>>> 458    Uint sz = MBC_FBLK_SZ(&blk->block_head);
>>> (gdb) backtrace
>>> #0  unlink_free_block (allctr=0x85f240, block=0x0, flags=0) at
>>> beam/erl_goodfit_alloc.c:458
>>> #1  0x0000000000444ee1 in get_free_block (allctr=0x85f240,
>>> size=<optimized out>, cand_blk=0x0, cand_size=0, flags=0) at
>>> beam/erl_goodfit_alloc.c:426
>>> #2  0x000000000043b6da in mbc_alloc_block (alcu_flgsp=<synthetic
>>> pointer>, blk_szp=<synthetic pointer>, size=<optimized out>,
>>> allctr=0x85f240) at beam/erl_alloc_util.c:1309
>>> #3  mbc_alloc (allctr=0x85f240, size=<optimized out>) at
>>> beam/erl_alloc_util.c:1451
>>> #4  0x0000000000440d7b in do_erts_alcu_alloc (size=32, extra=0x85f240,
>>> type=148) at beam/erl_alloc_util.c:3530
>>> #5  erts_alcu_alloc_thr_pref (type=148, extra=<optimized out>,
>>> size=<optimized out>) at beam/erl_alloc_util.c:3607
>>> #6  0x0000000000490595 in erts_alloc (size=32, type=18967) at
>>> beam/erl_alloc.h:208
>>> #7  new_message_buffer (size=0) at beam/erl_message.c:72
>>> #8  erts_alloc_message_heap_state (statep=0x2aaaef380c4c,
>>> receiver_locks=0x2aaaef380cb0, receiver=0x2aaaac9ccac8, ohpp=<synthetic
>>> pointer>, bpp=<synthetic pointer>, size=0) at beam/global.h:1017
>>> #9  erts_send_message (sender=0x2aaaac9cd118, receiver=0x2aaaac9ccac8,
>>> receiver_locks=0x2aaaef380cb0, message=513931, flags=<optimized out>) at
>>> beam/erl_message.c:1039
>>> #10 0x0000000000476350 in do_send (p=0x2aaaac9cd118, to=550027,
>>> msg=513931, suspend=1, refp=<optimized out>) at beam/bif.c:2025
>>> #11 0x0000000000476bf0 in erl_send (p=0x2aaaac9cd118, to=550027,
>>> msg=513931) at beam/bif.c:2138
>>> #12 0x000000000052d1d8 in process_main () at beam/beam_emu.c:2558
>>> #13 0x0000000000491463 in sched_thread_func (vesdp=0x2aaaac34de40) at
>>> beam/erl_process.c:5632
>>> #14 0x0000000000590440 in thr_wrapper (vtwd=0x7fffffffd7e0) at
>>> pthread/ethread.c:106
>>> #15 0x00002aaaab3ffe9a in start_thread (arg=0x2aaaef381700) at
>>> pthread_create.c:308
>>> #16 0x00002aaaab911cbd in clone () at
>>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
>>> #17 0x0000000000000000 in ?? ()
>>> (gdb)
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> erlang-questions mailing list
>>> 
>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>
>>
>>
>
>
> _______________________________________________
> erlang-questions mailing list
> 
> http://erlang.org/mailman/listinfo/erlang-questions
>



More information about the erlang-questions mailing list