[erlang-questions] Segfault with Erlang R22

[Mikael Pettersson]

On Fri, Oct 18, 2019 at 4:34 PM Bekes, Andras G
<Andras.Bekes@REDACTED> wrote:
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> Hi All,
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> After upgrading to Erlang R22, my software crashes the Erlang VM with Segmentation fault.
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> It happens rarely, only after several days of test workload, so I can’t really reproduce.
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>
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> I made more than 10 core dumps so far, loaded them into gdb, and all of them died at these 2 crash points:
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> Program terminated with signal 11, Segmentation fault.
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> #0  process_main (x_reg_array=0x20002, f_reg_array=0x2ade29280590) at x86_64-unknown-linux-gnu/opt/smp/beam_hot.h:4064
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> 4064      if (is_not_tuple(r(0))) {
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>
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> or
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> #0  process_main (x_reg_array=0x20002, f_reg_array=0x2) at x86_64-unknown-linux-gnu/opt/smp/beam_hot.h:5252
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> 5252          c_p->seq_trace_lastcnt = unsigned_val(SEQ_TRACE_TOKEN_SERIAL(c_p));
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> The software is not doing any tracing when the crash happens, nor does it have any NIFs.

I think you should open a bug report in the erlang bug tracker.

The second crash site above is in the remove_message() function, in a
block where ERL_MESSAGE_TOKEN(msgp)
is neither NIL nor am_undefined, but SEQ_TRACE_TOKEN(c_p) is invalid
(not the expected 5-tuple).

Maybe printing *c_p in gdb when that happens could shed some light.

/Mikael