https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103444
--- Comment #4 from kargl at gcc dot gnu.org --- This is as far as I have gotten on this bug. I don't know if this is a race condition in libgfortran's async_close(), a problem with gcc internal threading modeling (i.e., __gthrw_), and problem with FreeBSD libthr. Pointers on how to go to the next step appreciated. I assume something in __threadid below is amiss. % gfcx -o z -fopenmp -g async_io_9.f90 && ./z % gdb ./z (gdb) b async.c:479 Breakpoint 1 at 0x200a77ff0: file ../../../gccx/libgfortran/io/async.c, line 479. (gdb) run Thread 1 hit Breakpoint 1, _gfortrani_async_close (au=0x201a49000) at ../../../gccx/libgfortran/io/async.c:479 479 if (au == NULL) (gdb) p *au $1 = {io_lock = 0x2006da908, lock = 0x2006da888, empty = true, id = { waiting = -1, low = 1, high = 1, done = {pending = 0, signal = 0x201a230a0}}, work = {pending = 0, signal = 0x201a23060}, emptysignal = {pending = 0, signal = 0x201a23080}, pdt = 0x201a4e000, thread = 0x201a12700, head = 0x0, tail = 0x0, error = {message = 0x0, cmp = 0x0, has_error = false, last_good_id = 0, family = 0, fatal_error = false}} (gdb) n 483 enqueue_close (au); (gdb) n 484 T_ERROR (__gthread_join, au->thread, NULL); (gdb) Thread 2 received signal SIGBUS, Bus error. [Switching to LWP 180470 of process 18692] 0x0000000200f1ad6a in _Unwind_ForcedUnwind (exc=0x201a12938, stop=0x20068a030 <thread_unwind_stop>, stop_argument=0x0) at ../../../gccx/libgcc/unwind.inc:215 215 exc->private_1 = (_Unwind_Ptr) stop; (gdb) run Thread 1 hit Breakpoint 1, _gfortrani_async_close (au=0x201a49000) at ../../../gccx/libgfortran/io/async.c:479 479 if (au == NULL) (gdb) n 483 enqueue_close (au); (gdb) n 484 T_ERROR (__gthread_join, au->thread, NULL); (gdb) s __gthread_join (__value_ptr=0x0, __threadid=0x201a12700) at ../libgcc/gthr-default.h:669 669 return __gthrw_(pthread_join) (__threadid, __value_ptr); (gdb) p __value_ptr $2 = (void **) 0x0 (gdb) p __threadid $3 = (__gthread_t) 0x201a12700 (gdb) p *__threadid $4 = {tid = 180471, lock = {m_owner = 0, m_flags = 0, m_ceilings = {0, 0}, m_rb_lnk = 0, m_spare = {0, 0}}, cycle = 0, locklevel = 0, critical_count = 0, sigblock = 0, fsigblock = 0, tle = { tqe_next = 0x201a12000, tqe_prev = 0x200699900 <_thread_list>}, gcle = { tqe_next = 0x0, tqe_prev = 0x0}, hle = {le_next = 0x0, le_prev = 0x20069a128}, wle = {tqe_next = 0x0, tqe_prev = 0x201a19080}, refcount = 1, start_routine = 0x200a764d0 <async_io>, arg = 0x201a1df00, attr = {sched_policy = 2, sched_inherit = 4, prio = 0, suspend = 0, flags = 2, stackaddr_attr = 0x7fffbfdfe000, stacksize_attr = 2097152, guardsize_attr = 4096, cpuset = 0x0, cpusetsize = 0}, cancel_enable = 1, cancel_pending = 0, cancel_point = 1, no_cancel = 0, cancel_async = 0, cancelling = 0, sigmask = {__bits = {0, 0, 0, 0}}, unblock_sigcancel = 0, in_sigsuspend = 0, deferred_siginfo = {si_signo = 0, si_errno = 0, si_code = 0, si_pid = 0, si_uid = 0, si_status = 0, si_addr = 0x0, si_value = {sival_int = 0, sival_ptr = 0x0, sigval_int = 0, sigval_ptr = 0x0}, _reason = {_fault = {_trapno = 0}, _timer = { _timerid = 0, _overrun = 0}, _mesgq = {_mqd = 0}, _poll = {_band = 0}, _capsicum = {_syscall = 0}, __spare__ = {__spare1__ = 0, __spare2__ = { 0, 0, 0, 0, 0, 0, 0}}}}, deferred_sigmask = {__bits = {0, 0, 0, 0}}, deferred_sigact = {__sigaction_u = {__sa_handler = 0x0, __sa_sigaction = 0x0}, sa_flags = 0, sa_mask = {__bits = {0, 0, 0, 0}}}, deferred_run = 0, force_exit = 0, state = PS_RUNNING, error = 0, joiner = 0x0, flags = 0, tlflags = 2, mq = {{tqh_first = 0x0, tqh_last = 0x201a128a8}, {tqh_first = 0x0, tqh_last = 0x201a128b8}, { tqh_first = 0x0, tqh_last = 0x201a128c8}, {tqh_first = 0x0, tqh_last = 0x201a128d8}, {tqh_first = 0x0, tqh_last = 0x201a128e8}, { tqh_first = 0x0, tqh_last = 0x201a128f8}}, ret = 0x0, specific = 0x0, specific_data_count = 0, rdlock_count = 0, rtld_bits = 0, tcb = 0x2006bc1c0, cleanup = 0x0, ex = {exception_class = 0, exception_cleanup = 0x0, private_1 = 0, private_2 = 0}, unwind_stackend = 0x7fffbfffe000, unwind_disabled = 0, magic = 3499860245, report_events = 0, event_mask = 0, event_buf = {event = TD_EVENT_NONE, th_p = 0, data = 0}, wchan = 0x0, mutex_obj = 0x2006da888, will_sleep = 0, nwaiter_defer = 0, robust_inited = 0, robust_list = 0, priv_robust_list = 0, inact_mtx = 0, defer_waiters = {0x20069a428, 0x0 <repeats 49 times>}, wake_addr = 0x200637000, sleepqueue = 0x201a19080, name = 0x0, dlerror_msg = '\000' <repeats 511 times>, dlerror_seen = 0} (gdb) s Thread 2 received signal SIGBUS, Bus error. [Switching to LWP 180472 of process 18709] 0x0000000200f1ad6a in _Unwind_ForcedUnwind (exc=0x201a12938, stop=0x20068a030 <thread_unwind_stop>, stop_argument=0x0) at ../../../gccx/libgcc/unwind.inc:215 215 exc->private_1 = (_Unwind_Ptr) stop;