autofs intermittently stops mounting a NFS share

Issue

• autofs intermittently does not mount one of the NFS mount points.
• Occasionally "ls -l" will detect mount point was not completed.
• Backtrace is as follows:

(gdb) info threads
  6 Thread 0x2b58d48caaf0 (LWP 5255)  do_sigwait (set=0x7fffa16cff90, sig=0x7fffa16d001c) at ../sysdeps/unix/sysv/linux/sigwait.c:65
  5 Thread 0x413e6940 (LWP 5266)  0x00002b58d463d4f6 in __poll (fds=0x413e4e80, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
  4 Thread 0x42b26940 (LWP 5264)  0x00002b58d463d4f6 in __poll (fds=0x42b24e80, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
  3 Thread 0x42125940 (LWP 5260)  0x00002b58d463d4f6 in __poll (fds=0x42123e80, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
  2 Thread 0x41724940 (LWP 5257)  0x00002b58d377af59 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
* 1 Thread 0x41713940 (LWP 5256)  0x00002b58d377b1c0 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0

(gdb) thread apply all backtrace

Thread 6 (Thread 0x2b58d48caaf0 (LWP 5255)):
#0  do_sigwait (set=0x7fffa16cff90, sig=0x7fffa16d001c) at ../sysdeps/unix/sysv/linux/sigwait.c:65
#1  0x00002b58d377e9ad in __sigwait (set=0x7fffa16cff90, sig=0x7fffa16d001c) at ../sysdeps/unix/sysv/linux/sigwait.c:100
#2  0x00002b58d331271b in statemachine (arg=<value optimized out>) at automount.c:1308
#3  0x00002b58d3313a2a in main (argc=-654606320, argv=0x2b58d8fb83f0) at automount.c:2206

Thread 5 (Thread 0x413e6940 (LWP 5266)):
#0  0x00002b58d463d4f6 in __poll (fds=0x413e4e80, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00002b58d3315534 in get_pkt (arg=<value optimized out>) at automount.c:857
#2  handle_packet (arg=<value optimized out>) at automount.c:1017
#3  handle_mounts (arg=<value optimized out>) at automount.c:1569
#4  0x00002b58d377677d in start_thread (arg=<value optimized out>) at pthread_create.c:301
#5  0x00002b58d46463ed in clone () from /lib64/libc.so.6

Thread 4 (Thread 0x42b26940 (LWP 5264)):
#0  0x00002b58d463d4f6 in __poll (fds=0x42b24e80, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00002b58d3315534 in get_pkt (arg=<value optimized out>) at automount.c:857
#2  handle_packet (arg=<value optimized out>) at automount.c:1017
#3  handle_mounts (arg=<value optimized out>) at automount.c:1569
#4  0x00002b58d377677d in start_thread (arg=<value optimized out>) at pthread_create.c:301
#5  0x00002b58d46463ed in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x42125940 (LWP 5260)):
#0  0x00002b58d463d4f6 in __poll (fds=0x42123e80, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00002b58d3315534 in get_pkt (arg=<value optimized out>) at automount.c:857
#2  handle_packet (arg=<value optimized out>) at automount.c:1017
#3  handle_mounts (arg=<value optimized out>) at automount.c:1569
#4  0x00002b58d377677d in start_thread (arg=<value optimized out>) at pthread_create.c:301
#5  0x00002b58d46463ed in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x41724940 (LWP 5257)):
#0  0x00002b58d377af59 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00002b58d3320f33 in st_queue_handler (arg=<value optimized out>) at state.c:1089
#2  0x00002b58d377677d in start_thread (arg=<value optimized out>) at pthread_create.c:301
#3  0x00002b58d46463ed in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x41713940 (LWP 5256)):
#0  0x00002b58d377b1c0 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00002b58d332969c in alarm_handler (arg=<value optimized out>) at alarm.c:226
#2  0x00002b58d377677d in start_thread (arg=<value optimized out>) at pthread_create.c:301
#3  0x00002b58d46463ed in clone () from /lib64/libc.so.6
(gdb)