<html><head><style type="text/css">.style1 {font-family: "Times New Roman";}</style></head><body>I observe a reproducible SEGV of the 21.3.8.4 VM on macos Catalina when<BR>
repeatedly recompiling a module that has a skeletal NIF with an upgrade<BR>
callback. The skeleton is based on the examples in the documentation<BR>
but I am assuming that I have made an error somewhere. I would be<BR>
grateful for any pointers.<BR>
<BR>
The very simple NIF library is attached, together with its makefile and<BR>
the Erlang module's source. Once built, the failure is seen very<BR>
quickly:<BR>
<BR>
$ erl<BR>
Erlang/OTP 21 [erts-10.3.5.3] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [hipe]<BR>
<BR>
Eshell V10.3.5.3 (abort with ^G)<BR>
1> c(rtc), rtc:foo(), rtc:bar().<BR>
ok<BR>
2> c(rtc), rtc:foo(), rtc:bar().<BR>
ok<BR>
3> c(rtc), rtc:foo(), rtc:bar().<BR>
Segmentation fault: 11<BR>
$<BR>
<BR>
The stack is<BR>
<BR>
* thread #10, name = '6_scheduler', stop reason = EXC_BAD_ACCESS (code=1, address=0x70)<BR>
frame #0: 0x000000001e41bc0e beam.smp`nif_resource_dtor at atomic.h:240<BR>
237 ETHR_AINT_T__ tmp;<BR>
238<BR>
239 tmp = incr;<BR>
-> 240 __asm__ __volatile__(<BR>
241 "lock; xadd" ETHR_AINT_SUFFIX__ " %0, %1" /* xadd didn't exist prior to the 486 */<BR>
242 : "=r"(tmp)<BR>
243 : "m"(var->counter), "0"(tmp)<BR>
<BR>
* thread #10, name = '6_scheduler', stop reason = EXC_BAD_ACCESS (code=1, address=0x70)<BR>
* frame #0: 0x000000001e41bc0e beam.smp`nif_resource_dtor at atomic.h:240<BR>
frame #1: 0x000000001e41bc07 beam.smp`nif_resource_dtor<BR>
frame #2: 0x000000001e41bc07 beam.smp`nif_resource_dtor<BR>
frame #3: 0x000000001e41bc07 beam.smp`nif_resource_dtor<BR>
frame #4: 0x000000001e41bc07 beam.smp`nif_resource_dtor<BR>
frame #5: 0x000000001e41bbf0 beam.smp`nif_resource_dtor(bin=0x000000001fc800f8)<BR>
frame #6: 0x000000001e3d390d beam.smp`sweep_off_heap(p=0x0000000020740778, fullsweep=<unavailable>) at erl_binary.h:453<BR>
frame #7: 0x000000001e3d73f7 beam.smp`do_minor(p=0x0000000020740778, live_hf_end=<unavailable>, mature=<unavailable>, mature_size=696, new_sz=376, objv=<unavailable>, nobj=3) at erl_gc.c:1674<BR>
frame #8: 0x000000001e3d9af4 beam.smp`garbage_collect(p=0x0000000020740778, live_hf_end=0xfffffffffffffff8, need=4, objv=0x000000001f7d4440, nobj=3, fcalls=3047, max_young_gen_usage=0) at erl_gc.c:1417<BR>
frame #9: 0x000000001e3dabb5 beam.smp`erts_garbage_collect_nobump(p=0x0000000020740778, need=<unavailable>, objv=<unavailable>, nobj=<unavailable>, fcalls=3047) at erl_gc.c:878<BR>
frame #10: 0x000000001e4e8097 beam.smp`process_main(x_reg_array=0x000000001f7d4440, f_reg_array=<unavailable>) at beam_hot.h:104<BR>
frame #11: 0x000000001e287916 beam.smp`sched_thread_func(vesdp=0x0000000020bb3400) at erl_process.c:8469<BR>
frame #12: 0x000000001e4cbd52 beam.smp`thr_wrapper(vtwd=0x00007ffee197c140) at ethread.c:118<BR>
frame #13: 0x00007fff692aa109 libsystem_pthread.dylib`_pthread_start + 148<BR>
frame #14: 0x00007fff692a5b8b libsystem_pthread.dylib`thread_start + 15<BR>
<BR>
Robert Harris<BR>
<BR>
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