Issue #18119 has been updated by jeremyevans0 (Jeremy Evans). I can reproduce this with current Ruby master on OpenBSD/amd64: ``` ruby(14812) in free(): write after free 0x64d22481cc0 Abort trap (core dumped) ``` The backtrace is slightly different than the one in the initial report, but still happens during GC sweeping: ``` #10 0x0000064ca16a414f in obj_free (objspace=0x64d224a05f0, obj=6926918549680) at gc.c:3428 #11 0x0000064ca16a3bc1 in gc_sweep_plane (objspace=0x64d224a05f0, heap=0x64d224a0820, p=6926918549680, bitset=1152921504606846975, ctx=0x64cb0945c28) at gc.c:5425 #12 0x0000064ca16a3684 in gc_sweep_page (objspace=0x64d224a05f0, heap=0x64d224a0820, ctx=0x64cb0945c28) at gc.c:5503 #13 0x0000064ca169f68d in gc_sweep_step (objspace=0x64d224a05f0, size_pool=0x64d224a07d0, heap=0x64d224a0820) at gc.c:5780 #14 0x0000064ca169d694 in gc_sweep (objspace=0x64d224a05f0) at gc.c:6005 #15 0x0000064ca16a9095 in gc_start (objspace=0x64d224a05f0, reason=256) at gc.c:9263 ``` ---------------------------------------- Bug #18119: Ractor crashes when instantiating classes https://bugs.ruby-lang.org/issues/18119#change-104349 * Author: peterzhu2118 (Peter Zhu) * Status: Assigned * Priority: Normal * Assignee: ko1 (Koichi Sasada) * ruby -v: ruby 3.1.0dev (2021-08-19T08:44:48Z master 6963f8f743) [x86_64-linux] * Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN ---------------------------------------- The following script crashes with a segfault (tested on Ubuntu 20.04 and macOS 11.5.2): ```ruby workers = (0...8).map do Ractor.new do loop do 100.times.map { Class.new } Ractor.yield nil end end end 100.times { Ractor.select(*workers) } ``` Crash error: ``` <internal:ractor>:267: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues. test.rb:4: [BUG] Segmentation fault at 0x0000000000000040 ruby 3.1.0dev (2021-08-19T08:44:48Z master 6963f8f743) [x86_64-linux] -- Control frame information ----------------------------------------------- c:0010 p:---- s:0033 e:000032 CFUNC :new c:0009 p:0011 s:0029 e:000028 BLOCK test.rb:4 [FINISH] c:0008 p:---- s:0026 e:000025 IFUNC c:0007 p:---- s:0023 e:000022 CFUNC :times c:0006 p:---- s:0020 e:000019 CFUNC :each c:0005 p:---- s:0017 e:000016 CFUNC :map c:0004 p:0007 s:0013 e:000012 BLOCK test.rb:4 [FINISH] c:0003 p:---- s:0010 e:000009 CFUNC :loop c:0002 p:0004 s:0006 e:000005 BLOCK test.rb:3 [FINISH] c:0001 p:---- s:0003 e:000002 (none) [FINISH] -- Ruby level backtrace information ---------------------------------------- test.rb:3:in `block (2 levels) in <main>' test.rb:3:in `loop' test.rb:4:in `block (3 levels) in <main>' test.rb:4:in `map' test.rb:4:in `each' test.rb:4:in `times' test.rb:4:in `block (4 levels) in <main>' test.rb:4:in `new' -- Machine register context ------------------------------------------------ RIP: 0x0000562c1f9cd2cb RBP: 0x00007f6c3736d378 RSP: 0x00007f6c368285f0 RAX: 0x00007f6c1c00e208 RBX: 0x00007f6c3736d378 RCX: 0x0000562c20ed8330 RDX: 0x0000000000000000 RDI: 0x00007f6c100095c0 RSI: 0x0000000000000000 R8: 0x0000000000000007 R9: 0x0000562c20ed8120 R10: 0x0000000000000022 R11: 0x0000562c21180760 R12: 0x0000000000000000 R13: 0x00007f6c3736c000 R14: 0x0000000000000000 R15: 0x00007f6c3736d378 EFL: 0x0000000000010202 -- C level backtrace information ------------------------------------------- /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_print_backtrace+0x11) [0x562c1f995e38] ../vm_dump.c:759 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_vm_bugreport) ../vm_dump.c:1041 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_bug_for_fatal_signal+0xec) [0x562c1f78a0bc] ../error.c:815 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(sigsegv+0x4d) [0x562c1f8ebcbd] ../signal.c:961 /lib/x86_64-linux-gnu/libpthread.so.0(__restore_rt+0x0) [0x7f6c3b2c63c0] /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_class_remove_from_super_subclasses+0x2b) [0x562c1f9cd2cb] ../class.c:99 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(obj_free+0x37a) [0x562c1f7ae95a] ../gc.c:3123 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_plane_sweep+0x21) [0x562c1f7aef3d] ../gc.c:5322 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_page_sweep) ../gc.c:5464 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_sweep_step) ../gc.c:5630 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_heap_prepare_minimum_pages+0x0) [0x562c1f7afd94] ../gc.c:5834 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_sweep) ../gc.c:5837 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_marks+0x1c0) [0x562c1f7b3df8] ../gc.c:8144 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(gc_start) ../gc.c:9013 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(heap_prepare+0x2f) [0x562c1f7b8b6f] ../gc.c:2131 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(heap_next_freepage) ../gc.c:2422 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(ractor_cache_slots) ../gc.c:2454 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(newobj_slowpath) ../gc.c:2495 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(newobj_slowpath_wb_protected) ../gc.c:2519 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(newobj_of0+0x5) [0x562c1f7b8ebd] ../gc.c:2562 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(newobj_of) ../gc.c:2572 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_wb_protected_newobj_of) ../gc.c:2596 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(class_alloc+0x5) [0x562c1f9cd49e] ../class.c:185 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_class_boot) ../class.c:230 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(class_call_alloc_func+0x5) [0x562c1f84e5d3] ../object.c:2075 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_class_alloc) ../object.c:2047 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_class_new_instance_pass_kw) ../object.c:2120 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_cfp_consistent_p+0x0) [0x562c1f96d6bc] ../vm_insnhelper.c:2989 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call_cfunc_with_frame) ../vm_insnhelper.c:2991 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_sendish+0x303) [0x562c1f978393] ../vm_insnhelper.c:4562 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_exec_core+0xcd) [0x562c1f98316d] ../insns.def:775 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_vm_exec+0x197) [0x562c1f978fc7] ../vm.c:2164 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(collect_i+0x12) [0x562c1fa27bf2] ../enum.c:608 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_vm_pop_frame+0x0) [0x562c1f976ba8] ../vm_insnhelper.c:3795 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_yield_with_cfunc) ../vm_insnhelper.c:3796 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(invoke_block_from_c_bh+0x10) [0x562c1f97d0d3] ../vm.c:1359 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_yield) ../vm.c:1399 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_yield_0) ../vm_eval.c:1350 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_yield_1) ../vm_eval.c:1356 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(int_dotimes+0x5c) [0x562c1f83a49c] ../numeric.c:5014 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_cfp_consistent_p+0x0) [0x562c1f97dd4f] ../vm_eval.c:135 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call0_cfunc_with_frame) ../vm_eval.c:137 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call0_cfunc) ../vm_eval.c:149 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call0_body) ../vm_eval.c:182 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_call0+0x1ea) [0x562c1f9812fa] ../vm_eval.c:72 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(iterate_method+0x3b) [0x562c1f981e9b] ../vm_eval.c:847 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_iterate0+0x101) [0x562c1f973001] ../vm_eval.c:1534 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_block_call_kw+0x76) [0x562c1f9731f6] ../vm_eval.c:1566 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(enumerator_block_call+0x59) [0x562c1fa358e9] ../enumerator.c:553 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_cfp_consistent_p+0x0) [0x562c1f97dd4f] ../vm_eval.c:135 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call0_cfunc_with_frame) ../vm_eval.c:137 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call0_cfunc) ../vm_eval.c:149 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call0_body) ../vm_eval.c:182 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_call0+0x1ea) [0x562c1f9812fa] ../vm_eval.c:72 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(iterate_method+0x3b) [0x562c1f981e9b] ../vm_eval.c:847 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_iterate0+0x101) [0x562c1f973001] ../vm_eval.c:1534 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_lambda_call+0x75) [0x562c1f973295] ../vm_eval.c:1633 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(enum_collect+0x5b) [0x562c1fa29acb] ../enum.c:647 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_cfp_consistent_p+0x0) [0x562c1f96d6bc] ../vm_insnhelper.c:2989 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call_cfunc_with_frame) ../vm_insnhelper.c:2991 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_sendish+0x303) [0x562c1f978393] ../vm_insnhelper.c:4562 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_exec_core+0x130) [0x562c1f9831d0] ../insns.def:756 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_vm_exec+0x197) [0x562c1f978fc7] ../vm.c:2164 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(invoke_block_from_c_bh+0x130) [0x562c1f97c85a] ../vm.c:1264 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_yield) ../vm.c:1399 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_yield_0) ../vm_eval.c:1350 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(loop_i) ../vm_eval.c:1449 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_vrescue2+0x114) [0x562c1f794694] ../eval.c:1023 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_rescue2+0x8e) [0x562c1f79490e] ../eval.c:1000 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_cfp_consistent_p+0x0) [0x562c1f96d6bc] ../vm_insnhelper.c:2989 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_call_cfunc_with_frame) ../vm_insnhelper.c:2991 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_sendish+0x303) [0x562c1f978393] ../vm_insnhelper.c:4562 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(vm_exec_core+0x130) [0x562c1f9831d0] ../insns.def:756 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_vm_exec+0x197) [0x562c1f978fc7] ../vm.c:2164 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(thread_do_start_proc+0x294) [0x562c1f930f24] ../thread.c:716 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(thread_do_start+0xc) [0x562c1f9336fc] ../thread.c:760 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(thread_start_func_2) ../thread.c:835 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(rb_native_cond_initialize+0x0) [0x562c1f933a09] ../thread_pthread.c:1051 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(register_cached_thread_and_wait) ../thread_pthread.c:1103 /home/spin/src/github.com/Shopify/ruby-master/install/bin/ruby(thread_start_func_1) ../thread_pthread.c:1058 /lib/x86_64-linux-gnu/libpthread.so.0(0x9609) [0x7f6c3b2ba609] /lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7f6c3b044293] ``` -- https://bugs.ruby-lang.org/