Bug #17667: Module#name needs synchronization

• Status: Closed
• Assignee: ko1 (Koichi Sasada)
• Target version: -
• ruby -v: ruby 3.1.0dev (2021-02-28T11:24:42Z master 80e2c45f55) [x86_64-linux]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN

[ko1 (Koichi Sasada)]

class C; @iv = 1; end
Ractor.new{
  loop{C.name}
}
class C
  0.step{|i| instance_variable_set("@iv#{i}", i)}
end

/home/ko1/ruby/src/trunk/test.rb:4: [BUG] Segmentation fault at 0x000056513df4ef10
ruby 3.1.0dev (2021-02-28T11:24:42Z master 80e2c45f55) [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0005 p:---- s:0017 e:000016 CFUNC  :name
c:0004 p:0011 s:0013 e:000012 BLOCK  /home/ko1/ruby/src/trunk/test.rb:4 [FINISH]
c:0003 p:---- s:0010 e:000009 CFUNC  :loop
c:0002 p:0004 s:0006 e:000005 BLOCK  /home/ko1/ruby/src/trunk/test.rb:4 [FINISH]
c:0001 p:---- s:0003 e:000002 (none) [FINISH]

-- Ruby level backtrace information ----------------------------------------
/home/ko1/ruby/src/trunk/test.rb:4:in `block in <main>'
/home/ko1/ruby/src/trunk/test.rb:4:in `loop'
/home/ko1/ruby/src/trunk/test.rb:4:in `block (2 levels) in <main>'
/home/ko1/ruby/src/trunk/test.rb:4:in `name'

-- Machine register context ------------------------------------------------
 RIP: 0x000056513dbe09dc RBP: 0x000000000000000e RSP: 0x00007f96276e2140
 RAX: 0x000056513df4ef10 RBX: 0x0000000000001238 RCX: 0x000000000000000d
 RDX: 0x0000000000000ee1 RDI: 0x000056513de6f040 RSI: 0x0000000000000001
  R8: 0x000056513deedb00  R9: 0x000056513dec70c0 R10: 0x0000000000000000
 R11: 0x00007f96276e2d29 R12: 0x00000000000040d8 R13: 0x000056513dea2470
 R14: 0x00000000000076d5 R15: 0xffffffffffffffff EFL: 0x0000000000010206

-- C level backtrace information -------------------------------------------
/home/ko1/ruby/build/trunk/miniruby(rb_print_backtrace+0x11) [0x56513dc7e67e] /home/ko1/ruby/src/trunk/vm_dump.c:758
/home/ko1/ruby/build/trunk/miniruby(rb_vm_bugreport) /home/ko1/ruby/src/trunk/vm_dump.c:1042
/home/ko1/ruby/build/trunk/miniruby(rb_bug_for_fatal_signal+0xf4) [0x56513da892e4] /home/ko1/ruby/src/trunk/error.c:801
/home/ko1/ruby/build/trunk/miniruby(sigsegv+0x4d) [0x56513dbd5cbd] /home/ko1/ruby/src/trunk/signal.c:960
/lib/x86_64-linux-gnu/libpthread.so.0(__restore_rt+0x0) [0x7f962b7283c0] ../sysdeps/pthread/funlockfile.c:28
/home/ko1/ruby/build/trunk/miniruby(find_table_entry_ind+0x5c) [0x56513dbe09dc] /home/ko1/ruby/src/trunk/st.c:839
/home/ko1/ruby/build/trunk/miniruby(rb_st_lookup+0x4a) [0x56513dbe16fa] /home/ko1/ruby/src/trunk/st.c:1021
/home/ko1/ruby/build/trunk/miniruby(classname+0x79) [0x56513dc46380] /home/ko1/ruby/src/trunk/variable.c:102
/home/ko1/ruby/build/trunk/miniruby(rb_mod_name+0x32) [0x56513dc46405] /home/ko1/ruby/src/trunk/variable.c:121
/home/ko1/ruby/build/trunk/miniruby(vm_call_cfunc_with_frame+0x11b) [0x56513dc562eb] /home/ko1/ruby/src/trunk/vm_insnhelper.c:2924
/home/ko1/ruby/build/trunk/miniruby(vm_sendish+0xe) [0x56513dc63957] /home/ko1/ruby/src/trunk/vm_insnhelper.c:4525

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

This appears to have been fixed between Ruby 3.1 and 3.2. Ruby 3.0 and 3.1 both instantly crash with the given example, whereas Ruby 3.2 does not crash even if given a minute.