From: "vo.x (Vit Ondruch)" <noreply@...>
Date: 2022-02-09T10:53:08+00:00
Subject: [ruby-core:107528] [Ruby master Bug#18257] SystemTap/DTrace coredump

Issue #18257 has been updated by vo.x (Vit Ondruch).


Some snippets from my debugging. Initially, I set the breakpoint to the place where the rb_mRubyVMFrozenCore is assigned:

~~~
(gdb) b vm.c:3388
No source file named vm.c.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (vm.c:3388) pending.
(gdb) r
Starting program: /usr/bin/ruby -e ''
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Breakpoint 1, Init_VM () at vm.c:3388
3388	    rb_mRubyVMFrozenCore = fcore;
Missing separate debuginfos, use: dnf debuginfo-install glibc-2.34-21.el9.ppc64le gmp-6.2.0-10.el9.ppc64le libxcrypt-4.4.18-3.el9.ppc64le zlib-1.2.11-31.el9.ppc64le
(gdb) n
3394	    mjit = rb_define_module_under(rb_cRubyVM, "MJIT");
~~~

Just for illustration, this is associated SystemTap output which confirms it happens quite early:

~~~
69244 obj.create Object :0
69244 obj.create fatal :0
69244 obj.create fatal :0
69244 obj.create Object :0
69244 obj.create ARGF.class :0
69244 obj.create SystemStackError :0
69244 obj.create NoMemoryError :0
~~~

Lets try to collect some information:

~~~
(gdb) call ruby_debug_print_v(rb_mRubyVMFrozenCore)
DBG> : 0x00000001000a09c8 [0     ] T_ICLASS 
(gdb) p *(*(struct RClass *)(rb_mRubyVMFrozenCore))->ptr.iv_tbl.entries
$1 = {hash = 30421, key = 3809, record = 4295625080}
(gdb) call ruby_debug_print_v(4295625080)
DBG> : 0x00000001000a0978 [0     ] T_STRING (String)RubyVM::FrozenCore
(gdb) p *(struct RString *)(4295625080)
$2 = {basic = {flags = 8685573, klass = 4295927560}, as = {heap = {len = 4195751036648060242, ptr = 0x6f436e657a6f7246 <error: Cannot access memory at address 0x6f436e657a6f7246>, aux = {capa = 25970, 
        shared = 25970}}, ary = "RubyVM::FrozenCore\000\000\000\000\000"}}
~~~

The `*(*(struct RClass *)(rb_mRubyVMFrozenCore))->ptr.iv_tbl.entries` seems to link to a `RubyVM::FrozenCore` string which seem to be reasonable. In ideal state, these values should be static, during the whole Ruby instance lifetime, right? But I suspect they change somehow, so lets try to setup some watch:

~~~
(gdb) watch ((struct RBasic *)(4295625080))->klass
Watchpoint 2: ((struct RBasic *)(4295625080))->klass
(gdb) c
Continuing.
~~~

And indeed, the breakpoint is triggered:

~~~
Old value = 4295927560
New value = 4295624320
heap_page_add_freeobj (obj=4295625080, page=0x100036d40, objspace=<optimized out>) at gc.c:1701
1701	    page->freelist = p;
(gdb) bt
#0  heap_page_add_freeobj (obj=4295625080, page=0x100036d40, objspace=<optimized out>) at gc.c:1701
#1  gc_page_sweep (sweep_page=0x100036d40, heap=0x100031658, objspace=<optimized out>) at gc.c:4923
#2  gc_sweep_step (objspace=objspace@entry=0x100031630, heap=heap@entry=0x100031658) at gc.c:5134
#3  0x00007ffff7bed128 in gc_sweep_continue (heap=<optimized out>, objspace=0x100031630) at gc.c:5202
#4  heap_prepare (heap=<optimized out>, objspace=0x100031630) at gc.c:2041
#5  heap_next_freepage (heap=<optimized out>, objspace=<optimized out>) at gc.c:2200
#6  ractor_cache_slots (cr=<optimized out>, objspace=<optimized out>) at gc.c:2219
#7  newobj_slowpath (wb_protected=1, cr=0x1000357f0, objspace=0x100031630, flags=53274, klass=0) at gc.c:2265
#8  newobj_slowpath_wb_protected (klass=klass@entry=0, flags=flags@entry=53274, objspace=0x100031630, cr=0x1000357f0) at gc.c:2284
#9  0x00007ffff7bed784 in newobj_of0 (cr=<optimized out>, wb_protected=1, flags=53274, klass=0) at gc.c:2322
#10 newobj_of (wb_protected=1, v3=0, v2=0, v1=0, flags=53274, klass=0) at gc.c:2333
#11 rb_imemo_new (type=<optimized out>, v1=0, v2=0, v3=0, v0=0) at gc.c:2418
#12 0x00007ffff7dce0cc in vm_ic_update (reg_ep=<optimized out>, val=<optimized out>, ic=<optimized out>, iseq=<optimized out>) at vm_insnhelper.c:4669
#13 vm_exec_core (ec=0x100031cf0, initial=<optimized out>, initial@entry=0) at insns.def:1043
#14 0x00007ffff7dd1710 in rb_vm_exec (ec=0x100031cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#15 0x00007ffff7dd29f4 in rb_iseq_eval (iseq=0x10004a410) at vm.c:2409
#16 0x00007ffff7c2ce68 in load_iseq_eval (fname=4295431320, ec=0x100031cf0) at load.c:594
#17 require_internal (ec=ec@entry=0x100031cf0, fname=<optimized out>, fname@entry=4295211000, exception=exception@entry=1) at load.c:1065
#18 0x00007ffff7c2e7f4 in rb_require_string (fname=4295211000) at load.c:1142
#19 0x00007ffff7c2e88c in rb_f_require (obj=<optimized out>, fname=<optimized out>) at load.c:838
#20 0x00007ffff7daf538 in ractor_safe_call_cfunc_1 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2750
#21 0x00007ffff7dc4900 in vm_call_cfunc_with_frame (ec=0x100031cf0, reg_cfp=0x7ffff75aff30, calling=<optimized out>) at vm_insnhelper.c:2926
#22 0x00007ffff7dc7644 in vm_sendish (ec=0x100031cf0, reg_cfp=0x7ffff75aff30, cd=0x100121e10, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#23 0x00007ffff7dcba5c in vm_exec_core (ec=0x100031cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#24 0x00007ffff7dd1710 in rb_vm_exec (ec=0x100031cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#25 0x00007ffff7dd29f4 in rb_iseq_eval (iseq=0x10003b988) at vm.c:2409
#26 0x00007ffff7c2ce68 in load_iseq_eval (fname=4295394400, ec=0x100031cf0) at load.c:594
#27 require_internal (ec=ec@entry=0x100031cf0, fname=<optimized out>, fname@entry=4295394680, exception=exception@entry=1) at load.c:1065
#28 0x00007ffff7c2e7f4 in rb_require_string (fname=4295394680) at load.c:1142
#29 0x00007ffff7c2e88c in rb_f_require (obj=<optimized out>, fname=<optimized out>) at load.c:838
#30 0x00007ffff7daf538 in ractor_safe_call_cfunc_1 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2750
#31 0x00007ffff7dc4900 in vm_call_cfunc_with_frame (ec=0x100031cf0, reg_cfp=0x7ffff75affa0, calling=<optimized out>) at vm_insnhelper.c:2926
#32 0x00007ffff7dc7644 in vm_sendish (ec=0x100031cf0, reg_cfp=0x7ffff75affa0, cd=0x100190580, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#33 0x00007ffff7dcba5c in vm_exec_core (ec=0x100031cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#34 0x00007ffff7dd1710 in rb_vm_exec (ec=0x100031cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#35 0x00007ffff7dd29f4 in rb_iseq_eval (iseq=0x1000689d8) at vm.c:2409
#36 0x00007ffff7df5f60 in rb_load_with_builtin_functions (feature_name=0x7ffff7e961c0 "gem_prelude", table=0x0) at builtin.c:54
#37 0x00007ffff7d2826c in ruby_init_prelude () at ruby.c:1498
#38 ruby_opt_init (opt=0x7fffffffe5a0) at ruby.c:1521
#39 ruby_opt_init (opt=0x7fffffffe5a0) at ruby.c:1506
#40 0x00007ffff7d299d8 in process_options (argc=0, argc@entry=3, argv=0x7fffffffee20, argv@entry=0x7fffffffee08, opt=opt@entry=0x7fffffffe5a0) at ruby.c:1951
#41 0x00007ffff7d2a778 in ruby_process_options (argc=<optimized out>, argv=0x7fffffffee08) at ruby.c:230
#42 0x00007ffff7bc5904 in ruby_options (argc=<optimized out>, argv=0x7fffffffee08) at eval.c:138
#43 0x0000000100000a60 in main (argc=<optimized out>, argv=<optimized out>) at ./main.c:50
~~~

And here is the associated SystemTap log to give rough overview when this happened:

~~~
69244 obj.create Object <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 obj.create IOError <main>:0
69244 -> Exception::initialize <main>:0
69244 <- Exception::initialize <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 obj.create ThreadGroup <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited <main>:0
69244 <- Class::inherited <main>:0
69244 -> Class::inherited ruby:0
69244 <- Class::inherited ruby:0
69244 -> Class::inherited ruby:0
69244 <- Class::inherited ruby:0
69244 -> BasicObject::singleton_method_added <internal:gc>:33
69244 <- BasicObject::singleton_method_added <internal:gc>:33
69244 -> Module::method_added <internal:gc>:37
69244 <- Module::method_added <internal:gc>:37
69244 -> BasicObject::singleton_method_added <internal:gc>:46
69244 <- BasicObject::singleton_method_added <internal:gc>:46
69244 -> BasicObject::singleton_method_added <internal:gc>:58
69244 <- BasicObject::singleton_method_added <internal:gc>:58
69244 -> BasicObject::singleton_method_added <internal:gc>:72
69244 <- BasicObject::singleton_method_added <internal:gc>:72
69244 -> BasicObject::singleton_method_added <internal:gc>:84
69244 <- BasicObject::singleton_method_added <internal:gc>:84
69244 -> BasicObject::singleton_method_added <internal:gc>:92
69244 <- BasicObject::singleton_method_added <internal:gc>:92
69244 -> BasicObject::singleton_method_added <internal:gc>:110
69244 <- BasicObject::singleton_method_added <internal:gc>:110
69244 -> BasicObject::singleton_method_added <internal:gc>:120
69244 <- BasicObject::singleton_method_added <internal:gc>:120
69244 -> BasicObject::singleton_method_added <internal:gc>:169
69244 <- BasicObject::singleton_method_added <internal:gc>:169
69244 -> BasicObject::singleton_method_added <internal:gc>:183
69244 <- BasicObject::singleton_method_added <internal:gc>:183
69244 -> BasicObject::singleton_method_added <internal:gc>:197
69244 <- BasicObject::singleton_method_added <internal:gc>:197
69244 -> BasicObject::singleton_method_added <internal:gc>:212
69244 <- BasicObject::singleton_method_added <internal:gc>:212
69244 -> BasicObject::singleton_method_added <internal:gc>:230
69244 <- BasicObject::singleton_method_added <internal:gc>:230
69244 -> Module::method_added <internal:gc>:236
69244 <- Module::method_added <internal:gc>:236
69244 -> Module::module_function <internal:gc>:240
69244 -> BasicObject::singleton_method_added <internal:gc>:240
69244 <- BasicObject::singleton_method_added <internal:gc>:240
69244 <- Module::module_function <internal:gc>:240
69244 -> BasicObject::singleton_method_added <internal:ractor>:262
69244 <- BasicObject::singleton_method_added <internal:ractor>:262
69244 -> BasicObject::singleton_method_added <internal:ractor>:273
69244 <- BasicObject::singleton_method_added <internal:ractor>:273
69244 -> BasicObject::singleton_method_added <internal:ractor>:287
69244 <- BasicObject::singleton_method_added <internal:ractor>:287
69244 -> BasicObject::singleton_method_added <internal:ractor>:342
69244 <- BasicObject::singleton_method_added <internal:ractor>:342
69244 -> BasicObject::singleton_method_added <internal:ractor>:415
69244 <- BasicObject::singleton_method_added <internal:ractor>:415
69244 -> RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:422
69244 -> BasicObject::singleton_method_added <internal:ractor>:422
69244 <- BasicObject::singleton_method_added <internal:ractor>:422
69244 <- RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:422
69244 -> Module::method_added <internal:ractor>:426
69244 <- Module::method_added <internal:ractor>:426
69244 -> Module::private <internal:ractor>:426
69244 <- Module::private <internal:ractor>:426
69244 -> RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:431
69244 -> Module::method_added <internal:ractor>:431
69244 <- Module::method_added <internal:ractor>:431
69244 <- RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:431
69244 -> BasicObject::singleton_method_added <internal:ractor>:493
69244 <- BasicObject::singleton_method_added <internal:ractor>:493
69244 -> Module::method_added <internal:ractor>:497
69244 <- Module::method_added <internal:ractor>:497
69244 -> Module::private <internal:ractor>:497
69244 <- Module::private <internal:ractor>:497
69244 -> Module::method_added <internal:ractor>:582
69244 <- Module::method_added <internal:ractor>:582
69244 -> RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:587
69244 -> Module::method_added <internal:ractor>:587
69244 <- Module::method_added <internal:ractor>:587
69244 <- RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:587
69244 -> BasicObject::singleton_method_added <internal:ractor>:626
69244 <- BasicObject::singleton_method_added <internal:ractor>:626
69244 -> Module::method_added <internal:ractor>:693
69244 <- Module::method_added <internal:ractor>:693
69244 -> Module::method_added <internal:ractor>:699
69244 <- Module::method_added <internal:ractor>:699
69244 -> RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:709
69244 -> Module::method_added <internal:ractor>:709
69244 <- Module::method_added <internal:ractor>:709
69244 <- RubyVM::FrozenCore::core#set_method_alias <internal:ractor>:709
69244 -> Module::method_added <internal:ractor>:712
69244 <- Module::method_added <internal:ractor>:712
69244 -> Module::attr_reader <internal:ractor>:717
69244 -> Module::method_added <internal:ractor>:717
69244 <- Module::method_added <internal:ractor>:717
69244 <- Module::attr_reader <internal:ractor>:717
69244 -> Module::method_added <internal:ractor>:733
69244 <- Module::method_added <internal:ractor>:733
69244 -> Module::method_added <internal:ractor>:752
69244 <- Module::method_added <internal:ractor>:752
69244 -> BasicObject::singleton_method_added <internal:ractor>:769
69244 <- BasicObject::singleton_method_added <internal:ractor>:769
69244 -> BasicObject::singleton_method_added <internal:ractor>:810
69244 <- BasicObject::singleton_method_added <internal:ractor>:810
69244 -> Module::method_added <internal:ractor>:823
69244 <- Module::method_added <internal:ractor>:823
69244 -> Module::method_added <internal:ractor>:828
69244 <- Module::method_added <internal:ractor>:828
69244 -> BasicObject::singleton_method_added <internal:ractor>:833
69244 <- BasicObject::singleton_method_added <internal:ractor>:833
69244 -> Module::method_added <internal:integer>:6
69244 <- Module::method_added <internal:integer>:6
69244 -> Module::method_added <internal:integer>:22
69244 <- Module::method_added <internal:integer>:22
69244 -> Module::method_added <internal:integer>:27
69244 <- Module::method_added <internal:integer>:27
69244 -> Module::method_added <internal:integer>:73
69244 <- Module::method_added <internal:integer>:73
69244 -> Module::method_added <internal:integer>:82
69244 <- Module::method_added <internal:integer>:82
69244 -> Module::method_added <internal:integer>:91
69244 <- Module::method_added <internal:integer>:91
69244 -> Module::method_added <internal:integer>:95
69244 <- Module::method_added <internal:integer>:95
69244 -> Module::method_added <internal:integer>:104
69244 <- Module::method_added <internal:integer>:104
69244 -> Module::method_added <internal:integer>:120
69244 <- Module::method_added <internal:integer>:120
69244 -> Module::method_added <internal:integer>:130
69244 <- Module::method_added <internal:integer>:130
69244 -> Module::method_added <internal:integer>:138
69244 <- Module::method_added <internal:integer>:138
69244 -> Module::method_added <internal:integer>:146
69244 <- Module::method_added <internal:integer>:146
69244 -> Module::method_added <internal:io>:62
69244 <- Module::method_added <internal:io>:62
69244 -> Module::method_added <internal:io>:120
69244 <- Module::method_added <internal:io>:120
69244 -> BasicObject::singleton_method_added <internal:dir>:14
69244 <- BasicObject::singleton_method_added <internal:dir>:14
69244 -> Module::method_added <internal:dir>:34
69244 <- Module::method_added <internal:dir>:34
69244 -> BasicObject::singleton_method_added <internal:dir>:42
69244 <- BasicObject::singleton_method_added <internal:dir>:42
69244 -> BasicObject::singleton_method_added <internal:dir>:133
69244 <- BasicObject::singleton_method_added <internal:dir>:133
69244 -> BasicObject::singleton_method_added <internal:ast>:34
69244 <- BasicObject::singleton_method_added <internal:ast>:34
69244 -> BasicObject::singleton_method_added <internal:ast>:49
69244 <- BasicObject::singleton_method_added <internal:ast>:49
69244 -> BasicObject::singleton_method_added <internal:ast>:68
69244 <- BasicObject::singleton_method_added <internal:ast>:68
69244 -> Module::method_added <internal:ast>:90
69244 <- Module::method_added <internal:ast>:90
69244 -> Module::method_added <internal:ast>:98
69244 <- Module::method_added <internal:ast>:98
69244 -> Module::method_added <internal:ast>:106
69244 <- Module::method_added <internal:ast>:106
69244 -> Module::method_added <internal:ast>:114
69244 <- Module::method_added <internal:ast>:114
69244 -> Module::method_added <internal:ast>:122
69244 <- Module::method_added <internal:ast>:122
69244 -> Module::method_added <internal:ast>:133
69244 <- Module::method_added <internal:ast>:133
69244 -> Module::method_added <internal:ast>:141
69244 <- Module::method_added <internal:ast>:141
69244 -> BasicObject::singleton_method_added <internal:trace_point>:95
69244 <- BasicObject::singleton_method_added <internal:trace_point>:95
69244 -> Module::method_added <internal:trace_point>:104
69244 <- Module::method_added <internal:trace_point>:104
69244 -> BasicObject::singleton_method_added <internal:trace_point>:117
69244 <- BasicObject::singleton_method_added <internal:trace_point>:117
69244 -> BasicObject::singleton_method_added <internal:trace_point>:134
69244 <- BasicObject::singleton_method_added <internal:trace_point>:134
69244 -> Module::method_added <internal:trace_point>:195
69244 <- Module::method_added <internal:trace_point>:195
69244 -> Module::method_added <internal:trace_point>:231
69244 <- Module::method_added <internal:trace_point>:231
69244 -> Module::method_added <internal:trace_point>:239
69244 <- Module::method_added <internal:trace_point>:239
69244 -> Module::method_added <internal:trace_point>:246
69244 <- Module::method_added <internal:trace_point>:246
69244 -> Module::method_added <internal:trace_point>:251
69244 <- Module::method_added <internal:trace_point>:251
69244 -> Module::method_added <internal:trace_point>:256
69244 <- Module::method_added <internal:trace_point>:256
69244 -> Module::method_added <internal:trace_point>:262
69244 <- Module::method_added <internal:trace_point>:262
69244 -> Module::method_added <internal:trace_point>:267
69244 <- Module::method_added <internal:trace_point>:267
69244 -> Module::method_added <internal:trace_point>:272
69244 <- Module::method_added <internal:trace_point>:272
69244 -> Module::method_added <internal:trace_point>:308
69244 <- Module::method_added <internal:trace_point>:308
69244 -> Module::method_added <internal:trace_point>:313
69244 <- Module::method_added <internal:trace_point>:313
69244 -> Module::method_added <internal:trace_point>:321
69244 <- Module::method_added <internal:trace_point>:321
69244 -> Module::method_added <internal:trace_point>:326
69244 <- Module::method_added <internal:trace_point>:326
69244 -> Module::method_added <internal:trace_point>:331
69244 <- Module::method_added <internal:trace_point>:331
69244 -> Module::method_added <internal:trace_point>:337
69244 <- Module::method_added <internal:trace_point>:337
69244 -> Module::method_added <internal:trace_point>:345
69244 <- Module::method_added <internal:trace_point>:345
69244 -> Module::method_added <internal:pack>:133
69244 <- Module::method_added <internal:pack>:133
69244 -> Module::method_added <internal:pack>:256
69244 <- Module::method_added <internal:pack>:256
69244 -> Module::method_added <internal:pack>:280
69244 <- Module::method_added <internal:pack>:280
69244 -> Module::module_function <internal:warning>:5
69244 <- Module::module_function <internal:warning>:5
69244 -> Module::method_added <internal:warning>:50
69244 <- Module::method_added <internal:warning>:50
69244 -> BasicObject::singleton_method_added <internal:warning>:50
69244 <- BasicObject::singleton_method_added <internal:warning>:50
69244 -> Module::method_added <internal:array>:12
69244 <- Module::method_added <internal:array>:12
69244 -> Module::method_added <internal:array>:26
69244 <- Module::method_added <internal:array>:26
69244 -> Module::method_added <internal:array>:58
69244 <- Module::method_added <internal:array>:58
69244 -> Module::method_added <internal:kernel>:18
69244 <- Module::method_added <internal:kernel>:18
69244 -> Module::method_added <internal:kernel>:47
69244 <- Module::method_added <internal:kernel>:47
69244 -> Module::method_added <internal:kernel>:67
69244 <- Module::method_added <internal:kernel>:67
69244 -> Module::method_added <internal:kernel>:89
69244 <- Module::method_added <internal:kernel>:89
69244 -> Module::method_added <internal:kernel>:120
69244 <- Module::method_added <internal:kernel>:120
69244 -> Module::method_added <internal:kernel>:144
69244 <- Module::method_added <internal:kernel>:144
69244 -> Module::module_function <internal:kernel>:151
69244 <- Module::module_function <internal:kernel>:151
69244 -> Module::method_added <internal:kernel>:171
69244 <- Module::method_added <internal:kernel>:171
69244 -> BasicObject::singleton_method_added <internal:kernel>:171
69244 <- BasicObject::singleton_method_added <internal:kernel>:171
69244 -> Module::method_added <internal:prelude>:3
69244 <- Module::method_added <internal:prelude>:3
69244 -> RubyVM::FrozenCore::core#set_method_alias <internal:prelude>:9
69244 -> Module::method_added <internal:prelude>:9
69244 <- Module::method_added <internal:prelude>:9
69244 <- RubyVM::FrozenCore::core#set_method_alias <internal:prelude>:9
69244 -> Module::method_added <internal:prelude>:13
69244 <- Module::method_added <internal:prelude>:13
69244 -> RubyVM::FrozenCore::core#set_method_alias <internal:prelude>:19
69244 -> Module::method_added <internal:prelude>:19
69244 <- Module::method_added <internal:prelude>:19
69244 <- RubyVM::FrozenCore::core#set_method_alias <internal:prelude>:19
69244 -> Module::private <internal:prelude>:21
69244 <- Module::private <internal:prelude>:21
69244 -> Kernel::require <internal:gem_prelude>:2
69244 -> IO::set_encoding <internal:gem_prelude>:2
69244 <- IO::set_encoding <internal:gem_prelude>:2
69244 -> IO::set_encoding <internal:gem_prelude>:2
69244 <- IO::set_encoding <internal:gem_prelude>:2
69244 gc.mark.begin
69244 gc.sweep.begin
69244 gc.sweep.end
69244 gc.mark.end
69244 -> Kernel::require /usr/share/rubygems/rubygems.rb:8
69244 -> IO::set_encoding /usr/share/rubygems/rubygems.rb:8
69244 <- IO::set_encoding /usr/share/rubygems/rubygems.rb:8
69244 -> IO::set_encoding /usr/share/rubygems/rubygems.rb:8
69244 <- IO::set_encoding /usr/share/rubygems/rubygems.rb:8
69244 -> String::start_with? /usr/lib64/ruby/rbconfig.rb:12
69244 <- String::start_with? /usr/lib64/ruby/rbconfig.rb:12
69244 -> File::dirname /usr/lib64/ruby/rbconfig.rb:16
69244 <- File::dirname /usr/lib64/ruby/rbconfig.rb:16
69244 -> String::chomp! /usr/lib64/ruby/rbconfig.rb:16
69244 <- String::chomp! /usr/lib64/ruby/rbconfig.rb:16
69244 gc.sweep.begin
~~~

And somebody might wonder what is the state of the object which should supposedly hold the `classname`:

~~~
(gdb) call ruby_debug_print_v(rb_mRubyVMFrozenCore)
DBG> : 0x00000001000a09c8 [3LM R ] T_ICLASS 
(gdb) p *(*(struct RClass *)(rb_mRubyVMFrozenCore))->ptr.iv_tbl.entries
$4 = {hash = 30421, key = 3809, record = 4295625080}
(gdb)  p *(struct RBasic *)(4295625080)
$5 = {flags = 0, klass = 4295624320}
(gdb) call ruby_debug_print_v(4295625080)
DBG> : 0x00000001000a0978 [0     ] T_NONE 
~~~

So while the `rb_mRubyVMFrozenCore` is still the same, the description object changed to `T_NONE`. Running even further, the content changes again in  `rb_dtrace_setup` call:

~~~
(gdb) c
Continuing.

Watchpoint 2: ((struct RBasic *)(4295625080))->klass

Old value = 4295624320
New value = 4295927560
0x00007ffff7bed4b4 in rb_wb_protected_newobj_of (klass=4295927560, flags=5) at gc.c:2356
2356	}
(gdb) bt
#0  0x00007ffff7bed4b4 in rb_wb_protected_newobj_of (klass=4295927560, flags=5) at gc.c:2356
#1  0x00007ffff7d4b86c in str_alloc (klass=<optimized out>) at string.c:773
#2  str_duplicate (str=4295960160, klass=<optimized out>) at string.c:1601
#3  rb_str_dup (str=4295960160) at string.c:1608
#4  0x00007ffff7da72ac in rb_class_path (klass=4295960120) at variable.c:173
#5  0x00007ffff7dc46a4 in rb_dtrace_setup (ec=<optimized out>, klass=4295960120, id=3137, args=0x7fffffffa198) at vm.c:449
#6  0x00007ffff7dd83c4 in vm_call0_cfunc_with_frame (argv=0x7fffffffa330, calling=0x7fffffffa1b8, ec=0x100031cf0) at vm_eval.c:124
#7  vm_call0_cfunc (argv=0x7fffffffa330, calling=0x7fffffffa1b8, ec=0x100031cf0) at vm_eval.c:149
#8  vm_call0_body (ec=ec@entry=0x100031cf0, calling=calling@entry=0x7fffffffa278, argv=argv@entry=0x7fffffffa330) at vm_eval.c:180
#9  0x00007ffff7ddb9a0 in vm_call0_cc (kw_splat=0, cc=0x100211230, argv=0x7fffffffa330, argc=1, id=3137, recv=4295625120, ec=0x100031cf0) at vm_eval.c:72
#10 rb_funcallv_scope (scope=CALL_FCALL, argv=0x7fffffffa330, argc=1, mid=3137, recv=4295625120) at vm_eval.c:1006
#11 rb_funcallv (recv=4295625120, mid=3137, argc=<optimized out>, argv=0x7fffffffa330) at vm_eval.c:1026
#12 0x00007ffff7c88f60 in rb_obj_dup (obj=<error reading variable: value has been optimized out>) at object.c:568
#13 rb_obj_dup (obj=<error reading variable: value has been optimized out>) at object.c:559
#14 0x00007ffff7daf4e4 in ractor_safe_call_cfunc_0 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2743
#15 0x00007ffff7dc4900 in vm_call_cfunc_with_frame (ec=0x100031cf0, reg_cfp=0x7ffff75afe18, calling=<optimized out>) at vm_insnhelper.c:2926
#16 0x00007ffff7dc7644 in vm_sendish (ec=0x100031cf0, reg_cfp=0x7ffff75afe18, cd=0x100218e70, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#17 0x00007ffff7dcba5c in vm_exec_core (ec=0x100031cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#18 0x00007ffff7dd1710 in rb_vm_exec (ec=0x100031cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#19 0x00007ffff7dd5b4c in invoke_block (captured=<optimized out>, captured=<optimized out>, opt_pc=<optimized out>, type=<optimized out>, cref=0x0, self=<optimized out>, iseq=<optimized out>, ec=0x100031cf0)
    at vm.c:1263
#20 invoke_iseq_block_from_c (me=0x0, is_lambda=<optimized out>, cref=0x0, passed_block_handler=0, kw_splat=0, argv=<optimized out>, argc=2, self=<optimized out>, captured=<optimized out>, ec=0x100031cf0)
    at vm.c:1335
#21 invoke_block_from_c_bh (ec=0x100031cf0, block_handler=<optimized out>, argc=<optimized out>, argv=<optimized out>, kw_splat=<optimized out>, passed_block_handler=0, cref=0x0, is_lambda=<optimized out>, 
    force_blockarg=0) at vm.c:1353
#22 0x00007ffff7dd6db4 in vm_yield (kw_splat=0, argv=0x7fffffffac68, argc=2, ec=<optimized out>) at vm.c:1398
#23 rb_yield_0 (argv=0x7fffffffac68, argc=2) at vm_eval.c:1331
#24 rb_yield_values2 (argc=<optimized out>, argv=0x7fffffffac68) at vm_eval.c:1377
#25 0x00007ffff7bf0300 in each_pair_i_fast (key=<optimized out>, value=<optimized out>, _=<optimized out>) at hash.c:3116
#26 0x00007ffff7beffe4 in hash_foreach_iter (key=<optimized out>, value=<optimized out>, argp=140737488335344, error=<optimized out>) at hash.c:1378
#27 0x00007ffff7d37378 in st_general_foreach (tab=0x100202120, func=0x7ffff7beffa0 <hash_foreach_iter>, replace=0x0, arg=140737488335344, check_p=<optimized out>) at st.c:1473
#28 0x00007ffff7bf3ba0 in hash_foreach_call (arg=140737488335344) at hash.c:1507
#29 0x00007ffff7bc2fa0 in rb_ensure (b_proc=0x7ffff7bf3a60 <hash_foreach_call>, data1=140737488335344, e_proc=0x7ffff7bf1f80 <hash_foreach_ensure>, data2=<optimized out>) at eval.c:1162
#30 0x00007ffff7bf63c0 in rb_hash_foreach (farg=0, func=0x7ffff7bf02c0 <each_pair_i_fast>, hash=4295229560) at hash.c:1527
#31 rb_hash_foreach (hash=4295229560, func=0x7ffff7bf02c0 <each_pair_i_fast>, farg=0) at hash.c:1517
#32 0x00007ffff7bf7480 in rb_hash_each_pair (hash=4295229560) at hash.c:3153
#33 0x00007ffff7daf4e4 in ractor_safe_call_cfunc_0 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2743
#34 0x00007ffff7dc4900 in vm_call_cfunc_with_frame (ec=0x100031cf0, reg_cfp=0x7ffff75afe88, calling=<optimized out>) at vm_insnhelper.c:2926
#35 0x00007ffff7dc7644 in vm_sendish (ec=0x100031cf0, reg_cfp=0x7ffff75afe88, cd=0x10022b6e0, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#36 0x00007ffff7dcbac8 in vm_exec_core (ec=0x100031cf0, initial=<optimized out>, initial@entry=0) at insns.def:770
#37 0x00007ffff7dd1710 in rb_vm_exec (ec=0x100031cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#38 0x00007ffff7dd29f4 in rb_iseq_eval (iseq=0x10004a410) at vm.c:2409
#39 0x00007ffff7c2ce68 in load_iseq_eval (fname=4295431320, ec=0x100031cf0) at load.c:594
#40 require_internal (ec=ec@entry=0x100031cf0, fname=<optimized out>, fname@entry=4295211000, exception=exception@entry=1) at load.c:1065
#41 0x00007ffff7c2e7f4 in rb_require_string (fname=4295211000) at load.c:1142
#42 0x00007ffff7c2e88c in rb_f_require (obj=<optimized out>, fname=<optimized out>) at load.c:838
#43 0x00007ffff7daf538 in ractor_safe_call_cfunc_1 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2750
#44 0x00007ffff7dc4900 in vm_call_cfunc_with_frame (ec=0x100031cf0, reg_cfp=0x7ffff75aff30, calling=<optimized out>) at vm_insnhelper.c:2926
#45 0x00007ffff7dc7644 in vm_sendish (ec=0x100031cf0, reg_cfp=0x7ffff75aff30, cd=0x100121e10, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#46 0x00007ffff7dcba5c in vm_exec_core (ec=0x100031cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#47 0x00007ffff7dd1710 in rb_vm_exec (ec=0x100031cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#48 0x00007ffff7dd29f4 in rb_iseq_eval (iseq=0x10003b988) at vm.c:2409
#49 0x00007ffff7c2ce68 in load_iseq_eval (fname=4295394400, ec=0x100031cf0) at load.c:594
#50 require_internal (ec=ec@entry=0x100031cf0, fname=<optimized out>, fname@entry=4295394680, exception=exception@entry=1) at load.c:1065
--Type <RET> for more, q to quit, c to continue without paging--q
Quit
(gdb) p *(*(struct RClass *)(rb_mRubyVMFrozenCore))->ptr.iv_tbl.entries
$10 = {hash = 30421, key = 3809, record = 4295625080}
(gdb) p *(struct RBasic *)(4295625080)
$11 = {flags = 0, klass = 4295927560}
~~~

I am not really sure what happens after this point ...

However, my assumption is that `RubyVM::FrozenCore::core#set_method_alias` in its form won't apper in the log anymore and there will be some rubbish instead.


[1] https://github.com/ruby/ruby/blob/v3_0_2/vm.c#L3388

----------------------------------------
Bug #18257: SystemTap/DTrace coredump
https://bugs.ruby-lang.org/issues/18257#change-96439

* Author: vo.x (Vit Ondruch)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [x86_64-linux]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
Testing Ruby with SystemTap on RHEL9 beta following these steps:

~~~
$ stap -v /usr/share/doc/ruby-doc/ruby-exercise.stp &
$ ruby -e '[1, 2, 3].push(4)'
~~~

I get the following error:

~~~
/usr/share/rubygems/rubygems/errors.rb:181: [BUG] Segmentation fault at 0x0000000000000014
ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [powerpc64le-linux]

-- Control frame information -----------------------------------------------
c:0008 p:0028 s:0032 e:000027 CLASS  /usr/share/rubygems/rubygems/errors.rb:181
c:0007 p:0110 s:0025 e:000024 CLASS  /usr/share/rubygems/rubygems/errors.rb:153
c:0006 p:0007 s:0022 e:000021 TOP    /usr/share/rubygems/rubygems/errors.rb:9 [FINISH]
c:0005 p:---- s:0019 e:000018 CFUNC  :require
c:0004 p:0037 s:0014 e:000013 TOP    /usr/share/rubygems/rubygems.rb:19 [FINISH]
c:0003 p:---- s:0011 e:000010 CFUNC  :require
c:0002 p:0012 s:0006 e:000005 TOP    <internal:gem_prelude>:2 [FINISH]
c:0001 p:0000 s:0003 E:0026c0 (none) [FINISH]

-- Ruby level backtrace information ----------------------------------------
<internal:gem_prelude>:2:in `<internal:gem_prelude>'
<internal:gem_prelude>:2:in `require'
/usr/share/rubygems/rubygems.rb:19:in `<top (required)>'
/usr/share/rubygems/rubygems.rb:19:in `require'
/usr/share/rubygems/rubygems/errors.rb:9:in `<top (required)>'
/usr/share/rubygems/rubygems/errors.rb:153:in `<module:Gem>'
/usr/share/rubygems/rubygems/errors.rb:181:in `<class:SourceFetchProblem>'

-- C level backtrace information -------------------------------------------
/lib64/libruby.so.3.0(0x7fffb3b06ba0) [0x7fffb3b06ba0]
/lib64/libruby.so.3.0(0x7fffb38d9680) [0x7fffb38d9680]
/lib64/libruby.so.3.0(0x7fffb3a4b9d8) [0x7fffb3a4b9d8]
linux-vdso64.so.1(__kernel_sigtramp_rt64+0x0) [0x7fffb3ca0464]
[0x7fffb3a67ff8]
/lib64/libruby.so.3.0(rb_str_dup+0x130) [0x7fffb3a6b950]
/lib64/libruby.so.3.0(rb_class_path+0x3c) [0x7fffb3ac72ac]
/lib64/libruby.so.3.0(rb_dtrace_setup+0x134) [0x7fffb3ae46a4]
[0x7fffb3ae4a00]
[0x7fffb3ae7644]
[0x7fffb3aeba5c]
/lib64/libruby.so.3.0(rb_vm_exec+0x140) [0x7fffb3af1710]
/lib64/libruby.so.3.0(rb_iseq_eval+0x164) [0x7fffb3af29f4]
[0x7fffb394ce68]
/lib64/libruby.so.3.0(rb_require_string+0x44) [0x7fffb394e7f4]
/lib64/libruby.so.3.0(rb_f_require+0x1c) [0x7fffb394e88c]
[0x7fffb3acf538]
[0x7fffb3ae4900]
[0x7fffb3ae7644]
[0x7fffb3aeba5c]
/lib64/libruby.so.3.0(rb_vm_exec+0x140) [0x7fffb3af1710]
/lib64/libruby.so.3.0(rb_iseq_eval+0x164) [0x7fffb3af29f4]
[0x7fffb394ce68]
/lib64/libruby.so.3.0(rb_require_string+0x44) [0x7fffb394e7f4]
/lib64/libruby.so.3.0(rb_f_require+0x1c) [0x7fffb394e88c]
[0x7fffb3acf538]
[0x7fffb3ae4900]
[0x7fffb3ae7644]
[0x7fffb3aeba5c]
/lib64/libruby.so.3.0(rb_vm_exec+0x140) [0x7fffb3af1710]
/lib64/libruby.so.3.0(rb_iseq_eval+0x164) [0x7fffb3af29f4]
[0x7fffb3b15f60]
[0x7fffb3a4826c]
[0x7fffb3a499d8]
/lib64/libruby.so.3.0(ruby_process_options+0x158) [0x7fffb3a4a778]
/lib64/libruby.so.3.0(ruby_options+0xf4) [0x7fffb38e5904]
[0x11a360a60]
[0x7fffb35d7ca4]
[0x7fffb35d7e80]

-- Other runtime information -----------------------------------------------

* Loaded script: ruby

* Loaded features:

    0 enumerator.so
    1 thread.rb
    2 rational.so
    3 complex.so
    4 ruby2_keywords.rb
    5 /usr/lib64/ruby/enc/encdb.so
    6 /usr/lib64/ruby/enc/trans/transdb.so
    7 /usr/lib64/ruby/rbconfig.rb
    8 /usr/share/rubygems/rubygems/compatibility.rb
    9 /usr/share/rubygems/rubygems/defaults.rb
   10 /usr/share/rubygems/rubygems/deprecate.rb

* Process memory map:

11a360000-11a370000 r-xp 00000000 fd:00 34097694                         /usr/bin/ruby
11a370000-11a380000 r--p 00000000 fd:00 34097694                         /usr/bin/ruby
11a380000-11a390000 rw-p 00010000 fd:00 34097694                         /usr/bin/ruby
1000d490000-1000d6b0000 rw-p 00000000 00:00 0                            [heap]
7fffaf470000-7fffaf8d0000 r--s 00000000 fd:00 67811909                   /usr/lib64/libruby.so.3.0.2
7fffaf8d0000-7fffaf8f0000 r--s 00000000 fd:00 34097694                   /usr/bin/ruby
7fffaf8f0000-7fffaf900000 r-xp 00000000 fd:00 100999014                  /usr/lib64/ruby/enc/trans/transdb.so
7fffaf900000-7fffaf910000 r--p 00000000 fd:00 100999014                  /usr/lib64/ruby/enc/trans/transdb.so
7fffaf910000-7fffaf920000 rw-p 00000000 00:00 0 
7fffaf920000-7fffaf930000 r-xp 00000000 fd:00 67811915                   /usr/lib64/ruby/enc/encdb.so
7fffaf930000-7fffaf940000 r--p 00000000 fd:00 67811915                   /usr/lib64/ruby/enc/encdb.so
7fffaf940000-7fffaf950000 rw-p 00000000 00:00 0 
7fffaf950000-7fffaf960000 ---p 00000000 00:00 0 
7fffaf960000-7fffafa10000 rw-p 00000000 00:00 0 
7fffafa10000-7fffafa20000 ---p 00000000 00:00 0 
7fffafa20000-7fffafad0000 rw-p 00000000 00:00 0 
7fffafad0000-7fffafae0000 ---p 00000000 00:00 0 
7fffafae0000-7fffafb90000 rw-p 00000000 00:00 0 
7fffafb90000-7fffafba0000 ---p 00000000 00:00 0 
7fffafba0000-7fffafc50000 rw-p 00000000 00:00 0 
7fffafc50000-7fffafc60000 ---p 00000000 00:00 0 
7fffafc60000-7fffafd10000 rw-p 00000000 00:00 0 
7fffafd10000-7fffafd20000 ---p 00000000 00:00 0 
7fffafd20000-7fffafdd0000 rw-p 00000000 00:00 0 
7fffafdd0000-7fffafde0000 ---p 00000000 00:00 0 
7fffafde0000-7fffafe90000 rw-p 00000000 00:00 0 
7fffafe90000-7fffafea0000 ---p 00000000 00:00 0 
7fffafea0000-7fffaff50000 rw-p 00000000 00:00 0 
7fffaff50000-7fffaff60000 ---p 00000000 00:00 0 
7fffaff60000-7fffb0010000 rw-p 00000000 00:00 0 
7fffb0010000-7fffb0020000 ---p 00000000 00:00 0 
7fffb0020000-7fffb00d0000 rw-p 00000000 00:00 0 
7fffb00d0000-7fffb00e0000 ---p 00000000 00:00 0 
7fffb00e0000-7fffb0190000 rw-p 00000000 00:00 0 
7fffb0190000-7fffb01a0000 ---p 00000000 00:00 0 
7fffb01a0000-7fffb0250000 rw-p 00000000 00:00 0 
7fffb0250000-7fffb0260000 ---p 00000000 00:00 0 
7fffb0260000-7fffb0310000 rw-p 00000000 00:00 0 
7fffb0310000-7fffb0320000 ---p 00000000 00:00 0 
7fffb0320000-7fffb03d0000 rw-p 00000000 00:00 0 
7fffb03d0000-7fffb03e0000 ---p 00000000 00:00 0 
7fffb03e0000-7fffb0490000 rw-p 00000000 00:00 0 
7fffb0490000-7fffb04a0000 ---p 00000000 00:00 0 
7fffb04a0000-7fffb0550000 rw-p 00000000 00:00 0 
7fffb0550000-7fffb0560000 ---p 00000000 00:00 0 
7fffb0560000-7fffb0610000 rw-p 00000000 00:00 0 
7fffb0610000-7fffb0620000 ---p 00000000 00:00 0 
7fffb0620000-7fffb06d0000 rw-p 00000000 00:00 0 
7fffb06d0000-7fffb06e0000 ---p 00000000 00:00 0 
7fffb06e0000-7fffb0790000 rw-p 00000000 00:00 0 
7fffb0790000-7fffb07a0000 ---p 00000000 00:00 0 
7fffb07a0000-7fffb0850000 rw-p 00000000 00:00 0 
7fffb0850000-7fffb0860000 ---p 00000000 00:00 0 
7fffb0860000-7fffb0910000 rw-p 00000000 00:00 0 
7fffb0910000-7fffb0920000 ---p 00000000 00:00 0 
7fffb0920000-7fffb09d0000 rw-p 00000000 00:00 0 
7fffb09d0000-7fffb09e0000 ---p 00000000 00:00 0 
7fffb09e0000-7fffb0a90000 rw-p 00000000 00:00 0 
7fffb0a90000-7fffb0aa0000 ---p 00000000 00:00 0 
7fffb0aa0000-7fffb0b50000 rw-p 00000000 00:00 0 
7fffb0b50000-7fffb0b60000 ---p 00000000 00:00 0 
7fffb0b60000-7fffb0c10000 rw-p 00000000 00:00 0 
7fffb0c10000-7fffb0c20000 ---p 00000000 00:00 0 
7fffb0c20000-7fffb0cd0000 rw-p 00000000 00:00 0 
7fffb0cd0000-7fffb0ce0000 ---p 00000000 00:00 0 
7fffb0ce0000-7fffb0d90000 rw-p 00000000 00:00 0 
7fffb0d90000-7fffb0da0000 ---p 00000000 00:00 0 
7fffb0da0000-7fffb0e50000 rw-p 00000000 00:00 0 
7fffb0e50000-7fffb0e60000 ---p 00000000 00:00 0 
7fffb0e60000-7fffb0f10000 rw-p 00000000 00:00 0 
7fffb0f10000-7fffb0f20000 ---p 00000000 00:00 0 
7fffb0f20000-7fffb0fd0000 rw-p 00000000 00:00 0 
7fffb0fd0000-7fffb0fe0000 ---p 00000000 00:00 0 
7fffb0fe0000-7fffb1090000 rw-p 00000000 00:00 0 
7fffb1090000-7fffb10a0000 ---p 00000000 00:00 0 
7fffb10a0000-7fffb32e0000 rw-p 00000000 00:00 0 
7fffb32e0000-7fffb3340000 r--p 00000000 fd:00 33555845                   /usr/lib/locale/en_US.utf8/LC_CTYPE
7fffb3340000-7fffb3420000 r-xp 00000000 fd:00 67172714                   /usr/lib64/libm.so.6
7fffb3420000-7fffb3430000 r--p 000d0000 fd:00 67172714                   /usr/lib64/libm.so.6
7fffb3430000-7fffb3440000 rw-p 000e0000 fd:00 67172714                   /usr/lib64/libm.so.6
7fffb3440000-7fffb3480000 r-xp 00000000 fd:00 67172871                   /usr/lib64/libcrypt.so.2.0.0
7fffb3480000-7fffb3490000 r--p 00030000 fd:00 67172871                   /usr/lib64/libcrypt.so.2.0.0
7fffb3490000-7fffb34a0000 rw-p 00000000 00:00 0 
7fffb34a0000-7fffb3540000 r-xp 00000000 fd:00 67172912                   /usr/lib64/libgmp.so.10.4.0
7fffb3540000-7fffb3550000 r--p 00090000 fd:00 67172912                   /usr/lib64/libgmp.so.10.4.0
7fffb3550000-7fffb3560000 rw-p 000a0000 fd:00 67172912                   /usr/lib64/libgmp.so.10.4.0
7fffb3560000-7fffb3580000 r-xp 00000000 fd:00 67172832                   /usr/lib64/libz.so.1.2.11
7fffb3580000-7fffb3590000 r--p 00010000 fd:00 67172832                   /usr/lib64/libz.so.1.2.11
7fffb3590000-7fffb35a0000 rw-p 00020000 fd:00 67172832                   /usr/lib64/libz.so.1.2.11
7fffb35a0000-7fffb37e0000 r-xp 00000000 fd:00 67172711                   /usr/lib64/libc.so.6
7fffb37e0000-7fffb37f0000 r--p 00230000 fd:00 67172711                   /usr/lib64/libc.so.6
7fffb37f0000-7fffb3800000 rw-p 00240000 fd:00 67172711                   /usr/lib64/libc.so.6
7fffb3800000-7fffb3c30000 r-xp 00000000 fd:00 67811909                   /usr/lib64/libruby.so.3.0.2
7fffb3c30000-7fffb3c40000 ---p 00430000 fd:00 67811909                   /usr/lib64/libruby.so.3.0.2
7fffb3c40000-7fffb3c50000 r--p 00430000 fd:00 67811909                   /usr/lib64/libruby.so.3.0.2
7fffb3c50000-7fffb3c60000 rw-p 00440000 fd:00 67811909                   /usr/lib64/libruby.so.3.0.2
7fffb3c60000-7fffb3c70000 rw-p 00000000 00:00 0 
7fffb3c70000-7fffb3c80000 r--s 00000000 fd:00 100673889                  /usr/lib64/gconv/gconv-modules.cache
7fffb3c80000-7fffb3ca0000 r--p 00000000 00:00 0                          [vvar]
7fffb3ca0000-7fffb3cb0000 r-xp 00000000 00:00 0                          [vdso]
7fffb3cb0000-7fffb3d00000 r-xp 00000000 fd:00 67172707                   /usr/lib64/ld64.so.2
7fffb3d00000-7fffb3d10000 r--p 00040000 fd:00 67172707                   /usr/lib64/ld64.so.2
7fffb3d10000-7fffb3d20000 rw-p 00050000 fd:00 67172707                   /usr/lib64/ld64.so.2
7fffdee00000-7fffdf600000 rw-p 00000000 00:00 0                          [stack]
~~~

This should be the full BT:

~~~
(gdb) bt
#0  0x00007fffa5711550 in uleb128 (p=0x10039917f10) at addr2line.c:200
#1  di_read_die (reader=reader@entry=0x10039917eb8, die=die@entry=0x10039917dc8) at addr2line.c:1343
#2  0x00007fffa5714574 in debug_info_read (offset=<optimized out>, lines=<optimized out>, traces=<optimized out>, num_traces=<optimized out>, reader=<optimized out>) at addr2line.c:1630
#3  fill_lines (num_traces=num_traces@entry=39, traces=traces@entry=0x7fffa585d778 <trace>, check_debuglink=check_debuglink@entry=0, objp=objp@entry=0x10039919370, lines=lines@entry=0x100399756f0, 
    offset=<optimized out>, offset@entry=0) at addr2line.c:1887
#4  0x00007fffa5714f28 in follow_debuglink (offset=0, lines=0x100399756f0, objp=0x10039919370, traces=<optimized out>, num_traces=39, debuglink=0x7fffa14e01e4 "ruby-3.0.2-155.el9.ppc64le.debug")
    at addr2line.c:574
#5  fill_lines (num_traces=num_traces@entry=39, traces=traces@entry=0x7fffa585d778 <trace>, check_debuglink=check_debuglink@entry=1, objp=0x10039919370, objp@entry=0x100399193f0, 
    lines=lines@entry=0x100399756f0, offset=<optimized out>, offset@entry=-1) at addr2line.c:1925
#6  0x00007fffa571576c in rb_dump_backtrace_with_lines (num_traces=<optimized out>, traces=0x7fffa585d778 <trace>) at addr2line.c:2286
#7  0x00007fffa5706bac in rb_print_backtrace () at vm_dump.c:760
#8  rb_vm_bugreport (ctx=<optimized out>) at vm_dump.c:998
#9  0x00007fffa54d9680 in rb_bug_for_fatal_signal (default_sighandler=0x0, sig=<optimized out>, ctx=0x100399197c0, fmt=0x7fffa574e8f0 "Segmentation fault at %p") at error.c:786
#10 0x00007fffa564b9d8 in sigsegv (sig=<optimized out>, info=0x1003991a540, ctx=0x100399197c0) at signal.c:960
#11 <signal handler called>
#12 0x00007fffa5667ff8 in str_new_frozen_buffer (klass=klass@entry=1100477014720, orig=orig@entry=1100476844400, copy_encoding=copy_encoding@entry=1) at string.c:1329
#13 0x00007fffa566b950 in str_new_frozen (orig=1100476844400, klass=1100477014720) at string.c:1297
#14 str_duplicate_setup (dup=1100478149120, str=1100476844400, klass=1100477014720) at string.c:1570
#15 str_duplicate (str=1100476844400, klass=1100477014720) at string.c:1602
#16 rb_str_dup (str=1100476844400) at string.c:1608
#17 0x00007fffa56c72ac in rb_class_path (klass=1100476844480) at variable.c:173
#18 0x00007fffa56e46a4 in rb_dtrace_setup (ec=<optimized out>, klass=1100476844480, id=159, args=0x7fffe9d953d8) at vm.c:449
#19 0x00007fffa56e4a00 in vm_call_cfunc_with_frame (ec=<optimized out>, reg_cfp=0x7fffa4ecfe50, calling=<optimized out>) at vm_insnhelper.c:2916
#20 0x00007fffa56e7644 in vm_sendish (ec=0x10039811cf0, reg_cfp=0x7fffa4ecfe50, cd=0x100399a8db0, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#21 0x00007fffa56eba5c in vm_exec_core (ec=0x10039811cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#22 0x00007fffa56f1710 in rb_vm_exec (ec=0x10039811cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#23 0x00007fffa56f29f4 in rb_iseq_eval (iseq=0x100398aa7c0) at vm.c:2409
#24 0x00007fffa554ce68 in load_iseq_eval (fname=1100477137480, ec=0x10039811cf0) at load.c:594
#25 require_internal (ec=ec@entry=0x10039811cf0, fname=<optimized out>, fname@entry=1100476430040, exception=exception@entry=1) at load.c:1065
#26 0x00007fffa554e7f4 in rb_require_string (fname=1100476430040) at load.c:1142
#27 0x00007fffa554e88c in rb_f_require (obj=<optimized out>, fname=<optimized out>) at load.c:838
#28 0x00007fffa56cf538 in ractor_safe_call_cfunc_1 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2750
#29 0x00007fffa56e4900 in vm_call_cfunc_with_frame (ec=0x10039811cf0, reg_cfp=0x7fffa4ecff30, calling=<optimized out>) at vm_insnhelper.c:2926
#30 0x00007fffa56e7644 in vm_sendish (ec=0x10039811cf0, reg_cfp=0x7fffa4ecff30, cd=0x10039901e50, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#31 0x00007fffa56eba5c in vm_exec_core (ec=0x10039811cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#32 0x00007fffa56f1710 in rb_vm_exec (ec=0x10039811cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#33 0x00007fffa56f29f4 in rb_iseq_eval (iseq=0x1003981b9a8) at vm.c:2409
#34 0x00007fffa554ce68 in load_iseq_eval (fname=1100476613760, ec=0x10039811cf0) at load.c:594
#35 require_internal (ec=ec@entry=0x10039811cf0, fname=<optimized out>, fname@entry=1100476614040, exception=exception@entry=1) at load.c:1065
#36 0x00007fffa554e7f4 in rb_require_string (fname=1100476614040) at load.c:1142
#37 0x00007fffa554e88c in rb_f_require (obj=<optimized out>, fname=<optimized out>) at load.c:838
#38 0x00007fffa56cf538 in ractor_safe_call_cfunc_1 (recv=<optimized out>, argc=<optimized out>, argv=<optimized out>, func=<optimized out>) at vm_insnhelper.c:2750
#39 0x00007fffa56e4900 in vm_call_cfunc_with_frame (ec=0x10039811cf0, reg_cfp=0x7fffa4ecffa0, calling=<optimized out>) at vm_insnhelper.c:2926
#40 0x00007fffa56e7644 in vm_sendish (ec=0x10039811cf0, reg_cfp=0x7fffa4ecffa0, cd=0x10039970580, block_handler=<optimized out>, method_explorer=<optimized out>) at vm_callinfo.h:336
#41 0x00007fffa56eba5c in vm_exec_core (ec=0x10039811cf0, initial=<optimized out>, initial@entry=0) at insns.def:789
#42 0x00007fffa56f1710 in rb_vm_exec (ec=0x10039811cf0, mjit_enable_p=<optimized out>) at vm.c:2172
#43 0x00007fffa56f29f4 in rb_iseq_eval (iseq=0x100398489f8) at vm.c:2409
#44 0x00007fffa5715f60 in rb_load_with_builtin_functions (feature_name=0x7fffa57b61c0 "gem_prelude", table=0x0) at builtin.c:54
#45 0x00007fffa564826c in ruby_init_prelude () at ruby.c:1498
#46 ruby_opt_init (opt=0x7fffe9d98690) at ruby.c:1521
#47 ruby_opt_init (opt=0x7fffe9d98690) at ruby.c:1506
#48 0x00007fffa56499d8 in process_options (argc=0, argc@entry=3, argv=0x7fffe9d98f10, argv@entry=0x7fffe9d98ef8, opt=opt@entry=0x7fffe9d98690) at ruby.c:1951
#49 0x00007fffa564a778 in ruby_process_options (argc=<optimized out>, argv=0x7fffe9d98ef8) at ruby.c:230
#50 0x00007fffa54e5904 in ruby_options (argc=<optimized out>, argv=0x7fffe9d98ef8) at eval.c:138
#51 0x000000010b860a60 in main (argc=<optimized out>, argv=<optimized out>) at ./main.c:50
~~~



-- 
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