Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffca1fc700 (LWP 3070)]
0x00007fffc95e426e in gw_read_backend_event (dcb=0x7fffc4006350) at /usr/local/skysql/maxscale/MaxScale/server/modules/protocol/mysql_backend.c:379
379                                             service_refresh_users(dcb->session->service);
Missing separate debuginfos, use: debuginfo-install cyrus-sasl-lib-2.1.23-13.el6_3.1.x86_64 glibc-2.12-1.149.el6_6.9.x86_64 gperftools-libs-2.0-11.el6.3.x86_64 keyutils-libs-1.4-5.el6.x86_64 krb5-libs-1.10.3-33.el6.x86_64 libaio-0.3.107-10.el6.x86_64 libcom_err-1.41.12-21.el6.x86_64 libcurl-7.19.7-40.el6_6.4.x86_64 libgcc-4.4.7-11.el6.x86_64 libidn-1.18-2.el6.x86_64 libselinux-2.0.94-5.8.el6.x86_64 libssh2-1.4.2-1.el6.x86_64 libstdc++-4.4.7-11.el6.x86_64 libunwind-1.1-2.el6.x86_64 nspr-4.10.6-1.el6_5.x86_64 nss-3.16.1-7.el6_5.x86_64 nss-softokn-freebl-3.14.3-22.el6_6.x86_64 nss-util-3.16.1-2.el6_5.x86_64 openldap-2.4.23-34.el6_5.1.x86_64 openssl-1.0.1e-30.el6.8.x86_64 pcre-7.8-6.el6.x86_64 zlib-1.2.3-29.el6.x86_64
(gdb) bt
#0  0x00007fffc95e426e in gw_read_backend_event (dcb=0x7fffc4006350) at /usr/local/skysql/maxscale/MaxScale/server/modules/protocol/mysql_backend.c:379
#1  0x00000000005638ea in process_pollq (thread_id=6) at /usr/local/skysql/maxscale/MaxScale/server/core/poll.c:933
#2  0x0000000000562f94 in poll_waitevents (arg=0x6) at /usr/local/skysql/maxscale/MaxScale/server/core/poll.c:690
#3  0x00007ffff70cd9d1 in start_thread () from /lib64/libpthread.so.0
#4  0x00007ffff5a3e8fd in clone () from /lib64/libc.so.6
(gdb) print dcb
$1 = (DCB *) 0x7fffc4006350
(gdb) print *dcb
$2 = {dcb_chk_top = CHK_NUM_DCB, dcb_errhandle_called = false, dcb_role = DCB_ROLE_REQUEST_HANDLER, dcb_initlock = {lock = 0}, evq = {next = 0x7fffc4001760, prev = 0x7fffc4003030, 
    pending_events = 0, processing_events = 8197, processing = 1, eventqlock = {lock = 0}, inserted = 692906, started = 692906}, fd = 58, state = DCB_STATE_POLLING, flags = 0, remote = 0x0, 
  user = 0x23e2e70 "peddy", ipv4 = {sin_family = 0, sin_port = 0, sin_addr = {s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}, protoname = 0x7fffc400ba80 "MySQLBackend", 
  protocol = 0x7fffc40070b0, session = 0x0, func = {read = 0x7fffc95e3747 <gw_read_backend_event>, write = 0x7fffc95e4fca <gw_MySQLWrite_backend>, 
    write_ready = 0x7fffc95e4baf <gw_write_backend_event>, error = 0x7fffc95e53e3 <gw_error_backend_event>, hangup = 0x7fffc95e5f81 <gw_backend_hangup>, accept = 0, 
    connect = 0x7fffc95e5a11 <gw_create_backend_connection>, close = 0x7fffc95e64a7 <gw_backend_close>, listen = 0, auth = 0x7fffc95e6ad4 <gw_change_user>, session = 0}, writeqlen = 0, 
  writeqlock = {lock = 0}, writeq = 0x0, delayqlock = {lock = 0}, delayq = 0x0, dcb_readqueue = 0x0, authlock = {lock = 0}, stats = {n_reads = 2, n_writes = 1, n_accepts = 0, n_buffered = 0, 
    n_high_water = 0, n_low_water = 0}, dcb_server_status = 5, next = 0x7fffc4002a00, nextpersistent = 0x0, persistentstart = 1440232290, service = 0x0, data = 0x0, memdata = {bitmask = {lock = {
        lock = 0}, bits = 0x7fffc40019d0 "", length = 32}, next = 0x0}, cb_lock = {lock = 0}, callbacks = 0x7fffc40264d0, pollinlock = {lock = 0}, pollinbusy = 0, readcheck = 0, polloutlock = {
    lock = 0}, polloutbusy = 0, writecheck = 0, last_read = 692906, high_water = 0, low_water = 0, server = 0x22f4400, ssl = 0x0, dcb_port = 3306, dcb_chk_tail = CHK_NUM_DCB}
(gdb)