(gdb) bt
#0  0xb7e109e7 in raise () from /lib/tls/libc.so.6
#1  0xb7e1231b in abort () from /lib/tls/libc.so.6
#2  0xb7e47365 in __fsetlocking () from /lib/tls/libc.so.6
#3  0xb7e4da07 in malloc_usable_size () from /lib/tls/libc.so.6
#4  0xb7e4dea2 in free () from /lib/tls/libc.so.6
#5  0xb791d805 in attempt_thread (data=0x812de60) at pbx_spool.c:110
#6  0xb7fceccd in start_thread () from /lib/tls/libpthread.so.0
#7  0xb7eb8b0e in clone () from /lib/tls/libc.so.6

(gdb) bt full
#0  0xb7e109e7 in raise () from /lib/tls/libc.so.6
No symbol table info available.
#1  0xb7e1231b in abort () from /lib/tls/libc.so.6
No symbol table info available.
#2  0xb7e47365 in __fsetlocking () from /lib/tls/libc.so.6
No symbol table info available.
#3  0xb7e4da07 in malloc_usable_size () from /lib/tls/libc.so.6
No symbol table info available.
#4  0xb7e4dea2 in free () from /lib/tls/libc.so.6
No symbol table info available.
#5  0xb791d805 in attempt_thread (data=0x812de60) at pbx_spool.c:110
        res = 0
        reason = 4
#6  0xb7fceccd in start_thread () from /lib/tls/libpthread.so.0
No symbol table info available.
#7  0xb7eb8b0e in clone () from /lib/tls/libc.so.6
No symbol table info available.

(gdb) thread apply all bt

Thread 14 (process 16644):
#0  0x00000293 in ?? ()
Cannot access memory at address 0x51f
#0  0xb7e109e7 in raise () from /lib/tls/libc.so.6