[ruby-core:31365] [Bug #3555] segvs since r28570

Issue #3555 has been updated by Narihiro Nakamura.


I found memory error on trunk:

$ cat /tmp/t.rb
require "/tmp/f.rb"

module Kernel
  def require
  end
  GC.start
  GC.stress = true
  10.times{ "a".dup }
end

$ cat /tmp/f.rb
require "/tmp/t"

$ valgrind ./ruby /tmp/f.rb

==11321== Memcheck, a memory error detector
==11321== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==11321== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info
==11321== Command: ./ruby /tmp/f.rb
==11321==
==11321== Invalid write of size 1
==11321==    at 0x814AF5D: rb_thread_mark (vm.c:1651)
==11321==    by 0x8065905: gc_mark_children (gc.c:1752)
==11321==    by 0x80654A2: gc_mark (gc.c:1546)
==11321==    by 0x80654DC: rb_gc_mark (gc.c:1552)
==11321==    by 0x814AB63: vm_mark_each_thread_func (vm.c:1475)
==11321==    by 0x80F0D2D: st_foreach (st.c:747)
==11321==    by 0x814ABD0: rb_vm_mark (vm.c:1498)
==11321==    by 0x8065905: gc_mark_children (gc.c:1752)
==11321==    by 0x80654A2: gc_mark (gc.c:1546)
==11321==    by 0x80654DC: rb_gc_mark (gc.c:1552)
==11321==    by 0x8066DB5: gc_marks (gc.c:2340)
==11321==    by 0x806662D: gc_lazy_sweep (gc.c:2067)
==11321==  Address 0x43928e4 is 4 bytes inside a block of size 20 free'd
==11321==    at 0x4024B3A: free (vg_replace_malloc.c:366)
==11321==    by 0x8064203: vm_xfree (gc.c:752)
==11321==    by 0x806435A: ruby_xfree (gc.c:800)
==11321==    by 0x8142E70: rb_free_method_entry (vm_method.c:185)
==11321==    by 0x8142DAC: rb_sweep_method_entry (vm_method.c:151)
==11321==    by 0x8066304: after_gc_sweep (gc.c:2020)
==11321==    by 0x8066622: gc_lazy_sweep (gc.c:2065)
==11321==    by 0x80649A6: rb_newobj_from_heap (gc.c:1044)
==11321==    by 0x8064A5F: rb_newobj (gc.c:1128)
==11321==    by 0x80F1EF6: str_alloc (string.c:378)
==11321==    by 0x80F3CF2: rb_str_resurrect (string.c:901)
==11321==    by 0x813D7C1: vm_exec_core (insns.def:379)
==11321==
==11321==
==11321== HEAP SUMMARY:
==11321==     in use at exit: 384,939 bytes in 14,320 blocks
==11321==   total heap usage: 16,121 allocs, 1,801 frees, 1,528,828 bytes allocated
==11321==
==11321== LEAK SUMMARY:
==11321==    definitely lost: 46,603 bytes in 1,639 blocks
==11321==    indirectly lost: 198,711 bytes in 7,706 blocks
==11321==      possibly lost: 164 bytes in 7 blocks
==11321==    still reachable: 139,461 bytes in 4,968 blocks
==11321==         suppressed: 0 bytes in 0 blocks
==11321== Rerun with --leak-check=full to see details of leaked memory
==11321==
==11321== For counts of detected and suppressed errors, rerun with: -v
==11321== ERROR SUMMARY: 2 errors from 1 contexts (suppressed: 29 from 10)

I will fix it.

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http://redmine.ruby-lang.org/issues/show/3555

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