请教GDB调试core文件的时候无法显示stack frame信息

我用kill -SIGSEGV <pid>产生了一个core文件，然后用gdb察看这个core文件，却得不到源文件的信息：
(gdb) info threads
  12 process 9730  0xffffe410 in ?? ()
  11 process 9731  0xffffe410 in ?? ()
  10 process 9732  0xffffe410 in ?? ()
  9 process 9733  0xffffe410 in ?? ()
  8 process 9734  0xffffe410 in ?? ()
  7 process 9735  0xffffe410 in ?? ()
  6 process 9765  0xffffe410 in ?? ()
  5 process 9766  0xffffe410 in ?? ()
  4 process 9767  0xffffe410 in ?? ()
  3 process 9768  0xffffe410 in ?? ()
  2 process 9861  0xffffe410 in ?? ()
* 1 process 9729  0x5570b3e7 in __mq_timedreceive_nocancel ()
   from /lib/tls/librt.so.1
   
(gdb) t 1
[Switching to thread 1 (process 9729)]#0  0x5570b3e7 in __mq_timedreceive_nocancel () from /lib/tls/librt.so.1
(gdb) bt   
#0  0x5570b3e7 in __mq_timedreceive_nocancel () from /lib/tls/librt.so.1
Cannot access memory at address 0xffffd8dc   

(gdb) t 5
[Switching to thread 5 (process 9766)]#0  0xffffe410 in ?? ()
(gdb) bt
#0  0xffffe410 in ?? ()
#1  0x59df55c8 in ?? ()
#2  0x00002400 in ?? ()
#3  0x00000000 in ?? ()

不知道是什么原因？大家是否碰到过类似的情况？谢谢！