[erlang-questions] Segfault in NIF call

[Sverker Eriksson]

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

fredrik@REDACTED 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) 
>
>
>   
> ------------------------------------------------------------------------
>
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