Symptom:
Assertion failure at sess/aaamgr/aaamgr_api.c:11449
  Function: sn_aaa_session_set_user_data()
  Expression: s->magic == ( ('A' << 24) | ('S' << 16) | ('E' << 8) | ('S') )
  Proclet: sessmgr (f=87000,i=196)
  Process: card=7 cpu=0 arch=X pid=8293 cpu=~2% argv0=sessmgr
  Crash time: 2014-Jan-18+00:27:01 UTC
  Recent errno: 11 Resource temporarily unavailable
  Stack (11224@0xffffb000):
    [f7e285a1/X] libc.so.6/kill() sp=0xffffb528
    [0a9cfcf3/X] sn_assert() sp=0xffffb558
    [08d93150/X] sn_aaa_session_set_user_data() sp=0xffffb588
    [034bc609/X] sessmgr_deallocate_callline() sp=0xffffd458
    [040fe669/X] sessmgr_gprs_drop_call() sp=0xffffd4d8
    [041aa328/X] sessmgr_gprs_delayed_smid_release_callback() sp=0xffffd508
   [051b261a/X] tlib_serv() sp=0xffffd548
    [051b233b/X] tlib_tmr_tick() sp=0xffffd578
    [046937df/X] snx_timer_service() sp=0xffffd598
    [0469217f/X] snx_fast_service() sp=0xffffd5c8
    [05c6a5a4/X] sessmgr_snx_tick_callback() sp=0xffffd5f8
    [0aa5fb06/X] sn_loop_run() sp=0xffffdb88
    [0a8497b4/X] main() sp=0xffffdbc8

Conditions:
This is SGSN/MME combo
15.0(52633) build