[erlang-questions] segfault erts-5.10.4 (R16B03-1)

[Lukas Larsson]

Hello,

On Tue, Sep 8, 2015 at 10:33 AM, Ahmed Omar <spawn.think@REDACTED> wrote:

> Hi,
> We have been experiencing a segfault on our servers running a custom
> version of Ejabberd. We managed to get a core file from the last crash
> This is what we see running gdb on it:
> ######
> Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/ld-linux-x86-64.so.2
> Core was generated by `/var/lib/ejabberd/erts-5.10.4/bin/beam.smp -K true
> -A 128 -P 2500000 -Q 500000'.
> Program terminated with signal 11, Segmentation fault.
> #0  0x000000000044d299 in link_free_block (allctr=0x15e32c0, block=0x128)
> at beam/erl_goodfit_alloc.c:439
> 439 beam/erl_goodfit_alloc.c: No such file or directory.
> in beam/erl_goodfit_alloc.c
> ######
>
> If we run bt full in gdb we get:
> ######
> (gdb) bt full
> #0  0x000000000044d299 in link_free_block (allctr=0x15e32c0, block=0x128)
> at beam/erl_goodfit_alloc.c:439
>         gfallctr = 0x15e32c0
>         blk = 0x128
>         sz = 0
>         i = <value optimized out>
> #1  0x00000000015e32c0 in ?? ()
> No symbol table info available.
> #2  0x0000000000442fa6 in mbc_realloc (allctr=0x7fe0848807a8, p=0x11f,
> size=Unhandled dwarf expression opcode 0xf3
> ) at beam/erl_alloc_util.c:2370
>         crr = 0x128
>         new_p = <value optimized out>
>         old_blk_sz = 287
>         blk = 0x117
>         new_blk = <value optimized out>
>         cand_blk = <value optimized out>
>         cand_blk_sz = <value optimized out>
>         blk_sz = 3748409
>         nxt_blk = 0x236
>         nxt_blk_sz = 22950592
>         is_last_blk = 296
>         get_blk_sz = 140602277246336
> #3  0x0000000000000000 in ?? ()
> No symbol table info available.
> #######
>
> Is there a way to get more information? maybe which driver made the
> realloc call?
>

Something is wrong/missing from this stacktrace. The gdb that you are using
does not seem to understand the dwarf2 extension (at least that's what I
guess after googling "Unhandled dwarf expression opcode 0xf3"), and can
only find two of the frames. Try to install a later version of gdb and then
do a bt full.


>
> Best Regards,
> - Ahmed Omar
> http://about.me/spawn.think/
>
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> http://erlang.org/mailman/listinfo/erlang-questions
>
>
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