[Vm-dev] Debugging VM crash, INVALID RECEIVER / a(n) bad class ??

[Mariano Martinez Peck]

On Mon, Nov 16, 2015 at 2:48 PM, Mariano Martinez Peck <
marianopeck at gmail.com> wrote:

>
>
> On Mon, Nov 16, 2015 at 1:07 PM, Nicolai Hess <nicolaihess at gmail.com>
> wrote:
>
>>
>> Hi Mariano, if you know the method that may cause this crash can you check
>> if it works if you recompile this method with the old compiler,
>> maybe this issue is responsible - wrong stack frame size :
>> 13854
>> <https://pharo.fogbugz.com/f/cases/13854/frameSize-calculated-wrongly-for-lineSegmentsDo>
>> frameSize calculated wrongly for #lineSegmentsDo:
>>
>>
> Hi Nicolai,
>
> Thanks for the pointer. I tried with your fix and I still get the same
> results (even after recompiling).
> However...if I swap back to old Compiler rather than OpalCompiler and I
> recompile everything, then I do not have anymore the crash.
> So it's definitively something related to Opal compilation, and probably,
> related to closures compilation.
> I will see if I find other opal issues opened in 4.0.
>
> Thanks!
>
>
>>
>>
>> 2015-11-16 17:00 GMT+01:00 Mariano Martinez Peck <marianopeck at gmail.com>:
>>
>>>
>>> Hi guys,
>>>
>>> I am debugging a Pharo VM crash I am having and I cannot figure out what
>>> it is exactly. I suspect it might be related to block closures compilation
>>> but I am not sure. I have a reproducible crash test under Pharo 4.0 and
>>> OSX.
>>>
>>> I built a VM in debug mode and I run it via gdb. This is the kind of
>>> info I am able to see:
>>>
>>> *Program received signal SIGSEGV, Segmentation fault.*
>>> *0x000ab66b in updatePointersInRangeFromto (memStart=924623948,
>>> memEnd=928201420) at
>>> /Users/mariano/Pharo/git/pharo-vm/src/vm/gcc3x-cointerp.c:40444*
>>> *40444 && (((longAt(fieldOop)) & MarkBit) != 0)) {*
>>> *(gdb) call printAllStacks()*
>>> *Process 0x30e228c4 priority 40*
>>> *0xbffb2e10 M FaAction class>block: 0x20ebb104: a(n) FaAction class*
>>> *0xbffb2e30 M BlockClosure(FaMemoryStoreSession)>register: 0x371d0968:
>>> a(n) BlockClosure*
>>> *0xbffb2e4c M INVALID RECEIVER>register: 0x371cfd54: a(n) bad class*
>>>
>>> *(callerContextOrNil == (nilObject())) ||
>>> (isContext(callerContextOrNil)) 48626*
>>> *0x3721e1f0 is not a context*
>>> *0x371c34b4 is not a context*
>>>
>>> And another crash:
>>>
>>> *Program received signal SIGSEGV, Segmentation fault.*
>>> *0x000ab66b in updatePointersInRangeFromto (memStart=924677864,
>>> memEnd=928262300) at
>>> /Users/mariano/Pharo/git/pharo-vm/src/vm/gcc3x-cointerp.c:40444*
>>> *40444 && (((longAt(fieldOop)) & MarkBit) != 0)) {*
>>> *(gdb) call printAllStacks()*
>>> *Process 0x30e228c4 priority 40*
>>> *0xbffb2de0 M INVALID RECEIVER>initialize 0x3722b9a0: a(n) bad class*
>>> *0xbffb2df8 M FaAction class(Behavior)>new 0x20ebb104: a(n) FaAction
>>> class*
>>> *0xbffb2e10 M FaAction class>block: 0x20ebb104: a(n) FaAction class*
>>> *0xbffb2e30 M INVALID RECEIVER>register: 0x371ddee0: a(n) bad class*
>>> *0xbffb2e4c M INVALID RECEIVER>register: 0x371dd328 is in old space*
>>>
>>> *(callerContextOrNil == (nilObject())) ||
>>> (isContext(callerContextOrNil)) 48626*
>>> *0x3722b750 is not a context*
>>> *[New Thread 0x1b43 of process 5886]*
>>> *[New Thread 0x1d2f of process 5886]*
>>> *[New Thread 0x1f07 of process 5886]*
>>> *[New Thread 0x1e07 of process 5886]*
>>>
>>> From what I can see in *#printActivationNameFor: aMethod receiver:
>>> anObject isBlock: isBlock firstTemporary: maybeMessage*
>>> It looks like if the memory address is not an OOP, nor forwarding
>>> pointer nor...
>>>
>>> It also seems like the above stack I can get is not the real cause but a
>>> side effect that makes GC to crash (#updatePointersInRangeFromto)
>>>
>>> As said, I have a way to reproduce the crash, and I already have the VM
>>> compiled in debug and gdb running. I can also attach the full output of the
>>> gdb stack.
>>>
>>> BTW.... in the output of the gdb I see lots of printings like:
>>>
>>> *(numStack + ReceiverIndex) < (lengthOf(theContext)) 45421*
>>> *(ReceiverIndex + contextSize) < (lengthOfbaseHeaderformat(oop, header2,
>>> fmt)) 40416*
>>>
>>>
>>> Any pointer is appreciated.
>>>
>>> Thanks!
>>>
>>> --
>>> Mariano
>>> http://marianopeck.wordpress.com
>>>
>>>
>>
>>
>
>
> --
> Mariano
> http://marianopeck.wordpress.com
>



-- 
Mariano
http://marianopeck.wordpress.com
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