From: s.wanabe@... Date: 2017-05-17T00:27:51+00:00 Subject: [ruby-core:81205] [Ruby trunk Bug#13566] A process freezes at the beginning of C level backtrace when a certain SEGV is occurred Issue #13566 has been updated by wanabe (_ wanabe). mrkn (Kenta Murata) wrote: > r15: 0x00007fff577eb7d0 rip: 0x0000000000000000 rfl: 0x0000000000010246 rb_dump_machine_register() shows "rip: 0x0000000000000000". And lldb on my environment shows that `uctx->uc_mcontext->__ss.__rip[-2]` is accessed by backtrace() in vm_dump.c. It makes main-thread stop by EXC_BAD_ACCESS. ``` $ lldb -p 936 (lldb) process attach --pid 936 Process 936 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xfffffffffffffffe) frame #0: 0x0000000105ccb599 ruby`backtrace(trace=0x0000000105d69cd0, size=) at vm_dump.c:478 475 unw_set_reg(&cursor, UNW_X86_64_R14, uctx->uc_mcontext->__ss.__r14); 476 unw_set_reg(&cursor, UNW_X86_64_R15, uctx->uc_mcontext->__ss.__r15); 477 ip = uctx->uc_mcontext->__ss.__rip; -> 478 if (((char*)ip)[-2] == 0x0f && ((char*)ip)[-1] == 5) { 479 /* signal received in syscall */ 480 trace[n++] = (void *)ip; 481 ip = *(unw_word_t*)uctx->uc_mcontext->__ss.__rsp; Executable module set to "/Users/wanabe/.rbenv/versions/trunk/bin/ruby". Architecture set to: x86_64-apple-macosx. (lldb) ``` It seems to be related to #12711. ---------------------------------------- Bug #13566: A process freezes at the beginning of C level backtrace when a certain SEGV is occurred https://bugs.ruby-lang.org/issues/13566#change-64856 * Author: mrkn (Kenta Murata) * Status: Open * Priority: Normal * Assignee: naruse (Yui NARUSE) * Target version: * ruby -v: ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16] * Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN ---------------------------------------- I found the issue that a process freezes at the beginning of C level backtrace printing when a certain SEGV is occurred. I've made a reproducible code in the freeze_on_segv branch of pycall project. You can check it by the following steps: ``` $ git clone git@github.com:mrkn/pycall.git $ git checkout -t origin/freeze_on_segv $ bundle install $ bin/runner callback.rb ``` When you succeed to reproduce the issue, you can see the following output: ``` $ bin/runner callback.rb {:rw_refcnt=>1} 42 42 {:res=>42} {#=>[#]} callback.rb:11: [BUG] Segmentation fault at 0x00000000000000 ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16] -- Crash Report log information -------------------------------------------- See Crash Report log file under the one of following: * ~/Library/Logs/DiagnosticReports * /Library/Logs/DiagnosticReports for more details. Don't forget to include the above Crash Report log file in bug reports. -- Control frame information ----------------------------------------------- c:0005 p:---- s:0021 e:000020 CFUNC :Py_DecRef c:0004 p:0105 s:0016 E:002530 TOP callback.rb:11 [FINISH] c:0003 p:---- s:0011 e:000010 CFUNC :load c:0002 p:0034 s:0006 e:000005 EVAL bin/runner:6 [FINISH] c:0001 p:0000 s:0003 E:0013a0 (none) [FINISH] -- Ruby level backtrace information ---------------------------------------- bin/runner:6:in `
' bin/runner:6:in `load' callback.rb:11:in `' callback.rb:11:in `Py_DecRef' -- Machine register context ------------------------------------------------ rax: 0x00007fbb43667950 rbx: 0x729546a3ab9700ab rcx: 0x00007fbb40d05190 rdx: 0x00007fbb40d05190 rdi: 0x0000000109057d10 rsi: 0x00007fbb411e0358 rbp: 0x00007fff577eb6c0 rsp: 0x00007fff577eb6b8 r8: 0x00007fff577eb6e0 r9: 0x00000001085e46a1 r10: 0x00007fff577eb610 r11: 0x0000000108ca1d30 r12: 0x0000000000000000 r13: 0x0000000000000001 r14: 0x729546a3ab9700ab r15: 0x00007fff577eb7d0 rip: 0x0000000000000000 rfl: 0x0000000000010246 -- C level backtrace information ------------------------------------------- ``` At this point, C-c doesn't work. -- https://bugs.ruby-lang.org/ Unsubscribe: