Description of problem:
System is integrated with Active Directory using sssd-1.8.0-32.el6. Sometimes
ssh login hangs.
Here is the relevant backtrace,
(gdb) bt full
#0  __lll_robust_lock_wait () at
../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S:90
No locals.
#1  0x00007f4fbdbf6352 in _L_robust_lock_261 () from /lib64/libpthread.so.0
No symbol table info available.
#2  0x00007f4fbdbf5eaf in __pthread_mutex_lock_full (mutex=0x7f4fbcf6c960) at
pthread_mutex_lock.c:220
        result = <value optimized out>
        ignore1 = 0
        ignore2 = -1124677280
        oldval = <value optimized out>
        id = 22405
#3  0x00007f4fbcd688b9 in ?? () from /lib64/libnss_sss.so.2
No symbol table info available.
#4  0x00007f4fbcd6a0ae in _nss_sss_initgroups_dyn () from
/lib64/libnss_sss.so.2
No symbol table info available.
#5  0x00007f4fbe5224ef in internal_getgrouplist (user=0x7f4fc1bdad70 "hmoe",
group=10000, size=0x7fff20a51be8, groupsp=0x7fff20a51be0, limit=65536) at
initgroups.c:111
        prev_start = 1
        fct = 0x7f4fbcd6a060 <_nss_sss_initgroups_dyn>
        cnt = <value optimized out>
        status = <value optimized out>
        no_more = <value optimized out>
        start = 1
        nip = <value optimized out>
#6  0x00007f4fbe5226f3 in initgroups (user=0x7f4fc1bdad70 "hmoe", group=10000)
at initgroups.c:218
        size = 139980449433952
        groups = 0x7f4fc1bd2e20
        ngroups = <value optimized out>
        result = <value optimized out>
        limit = 65536
#7  0x00007f4fc1150608 in do_setusercontext (pw=0x7f4fc1bdade0) at
session.c:1511
        chroot_path = <value optimized out>
        tmp = <value optimized out>
#8  0x00007f4fc1142dd9 in privsep_postauth (ac=<value optimized out>, av=<value
optimized out>) at sshd.c:766
        rnd = {936555773, 1880375212, 922088415, 1321770366, 377427977,
611311796, 2534983324, 2198634067, 435483574, 4168116924, 732377044, 250646309,
1755156249, 3209214875, 2382686512, 2492701619, 3987942985, 1407168765,
57756104, 1250117280, 3036598124, 3298690322,
          4190669153, 4036601091, 1773497098, 1232221315, 303312863,
4254496725, 3711703297, 917057913, 3979243307, 1951661136, 1604175774,
867058568, 3283589179, 3909329750, 3134168408, 1504716533, 332693500,
3790035712, 791737430, 2373260857, 157528450, 2860961984,
          2934531016, 3944411632, 4034697971, 1084799323, 4038894559,
3253401426, 897473069, 2584532822, 1064753446, 2772077622, 392592177,
1393061205, 644312431, 1588781991, 2965181789, 2815372288, 423392069,
2548277015, 1761631767, 3884325217, 1623331722, 2419669128,
          2693832816, 246024058, 645731415, 1103796295, 2083695426, 3815145032,
1892333819, 4029800118, 3749505427, 313395916, 1355996950, 2768788407,
77783347, 989629699, 3125964244, 3505727532, 901406831, 595009439, 1588460978,
4112643443, 1179631195, 1530502462,
          1220152185, 3386284336, 1781571147, 1569340433, 2927963814,
1853365364, 263581098, 2317769197, 2896861565, 2936846182, 1387269176,
3275600550, 405363548, 217501531, 3036197859, 1679181792, 2704958255,
3805625712, 1609896136, 4189557842, 1184476103, 3503562732,
          3262813846, 134995913, 1347652670, 2784105721, 2582009394,
1469878796, 1575880215, 3986105369, 2837606260, 485821941, 2849068402,
1909568639, 2901375155, 1515048538, 697415669, 1976625630, 2128039539,
2349943477, 2224372163, 2525780203, 1386991886, 2454621619,
          381679343, 4044057497, 3219267011, 3833809743, 1743628179,
1364792988, 2514449890, 4256427109, 1022270678, 1193696300, 608927931,
1311121210, 2946660668, 3714393999, 3757312217, 4187249283, 4292758235,
1334056882, 3282701704, 3439202107, 1363897691,
          1255124965, 3575154627, 1660505854, 352798943, 1180424523,
1347275584, 3697822330, 714117673, 632709650, 3855108718, 3671068218,
1696236926, 3887046628, 1102324950, 1715631699, 3460467772, 3694785080,
1445149820, 4085456427, 3403883864, 51436896, 2880083489,
          1246272445, 1719603281, 567985145, 3876052020, 2313003133,
3741101985, 3873792528, 2966053358, 4249127390, 3466513438, 3233876594,
948090623, 2109115534, 2955686220, 4008609810, 3559393636, 2931782622,
959831707, 3592826234, 2003999294, 3449609980, 2771858447,
          2248048231, 2605550085, 2514298485...}
#9  main (ac=<value optimized out>, av=<value optimized out>) at sshd.c:2057
        opt = <value optimized out>
        i = <value optimized out>
        on = 1
        sock_in = 3
        sock_out = 3
        newsock = -1
        remote_ip = 0x7f4fc1bd0820 "139.107.166.110"
        test_user = 0x7fff20a52110 "SSH-2.0-OpenSSH_6.0p1 Debian-3"
        test_host = 0x3 <Address 0x3 out of bounds>
        test_addr = 0x3 <Address 0x3 out of bounds>
        remote_port = 59451
        line = <value optimized out>
        p = <value optimized out>
        cp = <value optimized out>
        config_s = {-1, -1}
        ibytes = <value optimized out>
        obytes = <value optimized out>
        new_umask = <value optimized out>
        key = <value optimized out>
        authctxt = 0x7f4fc1bd01e0
Version-Release number of selected component (if applicable):
sssd-1.8.0-32.el6