investigating a ghost in the machine

egdb-output.txt

Thread 3 hit Breakpoint 1, event_queue_insert (base=0xba9a8534800, 
    ev=0xba76e0afeb0 <i8253_channel+32>, queue=1) at event.c:879
879                     event_errx(1, "%s: %p(fd %d) already on queue %x", __func__,
(gdb) l
874             if (ev->ev_flags & queue) {
875                     /* Double insertion is possible for active events */
876                     if (queue & EVLIST_ACTIVE)
877                             return;
878
879                     event_errx(1, "%s: %p(fd %d) already on queue %x", __func__,
880                                ev, ev->ev_fd, queue);
881             }
882
883             if (~ev->ev_flags & EVLIST_INTERNAL)
(gdb) p ev
$1 = (struct event *) 0xba76e0afeb0 <i8253_channel+32>
(gdb) p *ev
$2 = {ev_next = {tqe_next = 0x0, tqe_prev = 0x0}, ev_active_next = {tqe_next = 0x0, tqe_prev = 0xba9a852e590}, ev_signal_next = {tqe_next = 0x0, tqe_prev = 0x0}, min_heap_idx = 0, 
  ev_base = 0xba9a8534800, ev_fd = -1, ev_events = 0, ev_ncalls = 0, ev_pncalls = 0xbaa47693f2a, ev_timeout = {tv_sec = 123701, tv_usec = 532558}, ev_pri = 0, 
  ev_callback = 0xba76e011bc0 <i8253_fire>, ev_arg = 0xba76e0afe90 <i8253_channel>, ev_res = 1, ev_flags = 129}




[Current thread is 3 (thread 159966)]
(gdb) bt
#0  event_queue_insert (base=0xba9a8534800, ev=0xba76e0afeb0 <i8253_channel+32>, queue=1) at event.c:879
#1  0x00000baa0f58667b in event_add (ev=0xba76e0afeb0 <i8253_channel+32>, tv=0xbaa47693ee8) at event.c:729
#2  0x00000ba76e011c6f in i8253_fire (fd=-1, type=1, arg=0xba76e0afe90 <i8253_channel>) at i8253.c:347
#3  0x00000baa0f58614f in event_process_active (base=0xba9a8534800) at event.c:333
#4  0x00000baa0f58587a in event_base_loop (base=0xba9a8534800, flags=0) at event.c:483
#5  0x00000baa0f5855d7 in event_loop (flags=0) at event.c:409
#6  0x00000baa0f585589 in event_dispatch () at event.c:347
#7  0x00000ba76e002696 in event_thread (arg=0x7f7ffffee5df) at vm.c:1363
#8  0x00000ba9c877da31 in _rthread_start (v=<optimized out>) at /usr/src/lib/librthread/rthread.c:96
#9  0x00000baa0b829118 in __tfork_thread () at /usr/src/lib/libc/arch/amd64/sys/tfork_thread.S:77
#10 0x0000000000000000 in ?? ()