Date: Thu, 5 Nov 2020 10:19:52 -0800 From: Pete Wright <pete@nomadlogic.org> To: questions list <freebsd-questions@freebsd.org> Subject: Helping understand cause of SIGSEGV Message-ID: <c2eab4b0-b10b-9db3-1aa3-1f61689e24e8@nomadlogic.org>
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i was hoping someone with more experience in C and threading can help me better understand this SIGSEGV fault I'm hitting. the background is I'm trying to get sysutils/fluent-bit working on 12.2-RELEASE as well as on CURRENT. I've created the following PR and upstream github issues: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=250825 https://github.com/fluent/fluent-bit/issues/2747 so where i am at now is i am able to generate a useful core file when it hits the fault and can step through it in lldb. here is the output from fluent-bit: |[2020/11/04 22:18:12] [debug] [task] created task=0x416410a0 id=0 OK [2020/11/04 22:18:12] [trace] [thread 0x416091c0] created (custom data at 0x416091e0, size=80 [2020/11/04 22:18:12] [engine] caught signal (SIGSEGV) #0 0x406d11ee in thr_sighandler() at /lib/libthr/thread/thr_sig.c:246 Abort trap (core dumped)| here's an example from one of the threads (the github link above has the full backtrace) from lldb: | thread #1, name = 'fluent-bit', stop reason = signal SIGABRT * frame #0: 0x000000004087100a libc.so.7`__sys_thr_kill at thr_kill.S:4 frame #1: 0x00000000407e6c84 libc.so.7`__raise(s=6) at raise.c:52:10 frame #2: 0x000000004089a5d9 libc.so.7`abort at abort.c:67:8 frame #3: 0x000000000034a7a8 fluent-bit`flb_signal_handler(signal=11) at fluent-bit.c:418:9 frame #4: 0x00000000406d1c20 libthr.so.3`handle_signal(actp=0x00007fffdfffc600, sig=11, info=0x00007fffdfffc9f0, ucp=0x00007fffdfffc680) at thr_sig.c:303:3 frame #5: 0x00000000406d11ef libthr.so.3`thr_sighandler(sig=11, info=0x00007fffdfffc9f0, _ucp=0x00007fffdfffc680) at thr_sig.c:246:2 frame #6: 0x00007fffffffe193 frame #7: 0x000000000036fe0c fluent-bit`tasks_start [inlined] output_params_set(th=0x00000000416091c0, data=0x000000004165d980, bytes=128, tag="random.0", tag_len=8, i_ins=0x0000000040e58000, out_plugin=0x0000000040e2dfc0, out_context=0x00000000416051e0, config=0x0000000040e19180) at flb_output.h:429:5 frame #8: 0x000000000036fd14 fluent-bit`tasks_start [inlined] flb_output_thread(task=0x00000000416410a0, i_ins=0x0000000040e58000, o_ins=0x0000000040e5b000, config=0x0000000040e19180, buf=0x000000004165d980, size=128, tag="random.0", tag_len=8) at flb_output.h:522 frame #9: 0x000000000036fab5 fluent-bit`tasks_start(in=0x0000000040e58000, config=0x0000000040e19180) at flb_engine_dispatch.c:190 frame #10: 0x000000000036f6fd fluent-bit`flb_engine_dispatch(id=0, in=0x0000000040e58000, config=0x0000000040e19180) at flb_engine_dispatch.c:293:5 frame #11: 0x000000000036ce10 fluent-bit`flb_engine_flush(config=0x0000000040e19180, in_force=0x0000000000000000) at flb_engine.c:85:9 frame #12: 0x000000000036d43a fluent-bit`flb_engine_start [inlined] flb_engine_handle_event(fd=20, mask=1, config=0x0000000040e19180) at flb_engine.c:292:13 frame #13: 0x000000000036d3e6 fluent-bit`flb_engine_start(config=0x0000000040e19180) at flb_engine.c:559 frame #14: 0x00000000003564ec fluent-bit`flb_lib_worker(data=0x0000000040e19180) at flb_lib.c:488:11 frame #15: 0x00000000406c87db libthr.so.3`thread_start(curthread=0x0000000040e12500) at thr_create.c:292:16 I was hoping someone here could help point me in the right direction as i'm kinda stuck but not sure where i should start looking? cheers, -pete| -- Pete Wright pete@nomadlogic.org @nomadlogicLA
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