Symptom:
Assertion failure at sess/sgsn/sgsn-app/s4_sm/s4_smn_modify_fsm.c:2356
  Note: Could not send modify req to dp-n
  Function: s4_smn_pgw_modify_handle_modify_cfm()
  Expression: 0
  Code: CRASH
  Proclet: sessmgr (f=87000,i=291)
  Process: card=8 cpu=0 arch=X pid=13931 cpu=~9% argv0=sessmgr
  Crash time: 2014-Apr-16+04:07:52 UTC
  Recent errno: 11 Resource temporarily unavailable
  Stack (121704@0xfffe0000):
    [ffffe430/X] __kernel_vsyscall() sp=0xfffe0118
    [0aa7f85f/X] sn_assert() sp=0xfffe0158
    [070ff89e/X] s4_smn_pgw_modify_handle_modify_cfm() sp=0xfffe1468
    [06fda561/X] SmGenReallocAccResAccept() sp=
    [06e7a5de/X] sma_ggsn_modify_handle_realloc_res_req() sp=
    [06fd50f8/X] SmGenModSessAccept() sp=
    [06d7d439/X] sma_ggsn_modify_handle_mod_sess_req() sp=
    [06cdcda3/X] SmGenReallocNwResInd() sp=
    [0716157c/X] s4_smn_pgw_modify_handle_ubr_req() sp=
    [070ee059/X] s4_smn_feed_s4_smn_update_bearer_req_event() sp=
    [0715ef2a/X] sessmgr_sgsn_smn_s4_sgsn_egtpc_callback() sp=
    [06c33edc/X] sessmgr_s4_sgsn_egtpc_callback() sp=
    [07714bda/X] egtpc_send_ind_evt() sp=
    [07760b2a/X] egtpc_handle_update_bearer_req_msg() sp=
    [076edcaf/X] egtpc_handle_tun_n_mob_mgmt_message() sp=
    [07735566/X] egtpc_handle_gtp_message() sp=
    [03cf11c1/X] sessmgr_egtp_handle_gtpc_message() sp=
    [03cf1837/X] sessmgr_egtp_dmed_rx_cb() sp=
    [05dc9064/X] sessmgr_receive_ipv4udp_packets.isra.65() sp=
    [05f89911/X] sessmgr_med_data_receive() sp=
    [0ab19d6c/X] sn_epoll_run_events() sp=
    [0ab1e211/X] sn_loop_run() sp=
    [0a8c1f6d/X] main() sp=

Conditions:
During overnight call model run, this crash is observed in system-test setup.