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

[Nicolai Hess]

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:



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
>
>
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