[Vm-dev] Re: Cog segmentation fault on Linux
Rob Withers
reefedjib at yahoo.com
Tue Jul 20 01:19:08 UTC 2010
Hi Eliot,
Got home from my new job and started looking into this. It turns out that this morning I found that I had a button bar that was stepping and part of the step was a Smalltalk garbageCollect to force collection before checking for instances. It may be something I don't need to do anymore, however it helps expose this seg fault. Both stack dumps were in the garbageCollect. I removed the button bar, uploaded the image, and ran it. CPU% dropped from 33% to 2%. I let it run all day. At some point it exited, for an unknown reason, as it was gone when I returned tonight.
I have reinstated the button bar, to help this bug occur, and uploaded it to the server.
Now I just need to enable -leakcheck. From sqUnixMain.c it looks like it takes an argument. What is that argument?
Thanks,
Rob
From: Eliot Miranda
Sent: Monday, July 19, 2010 1:47 PM
To: Rob Withers
Cc: Squeak Virtual Machine Development Discussion
Subject: Re: Cog segmentation fault on Linux
Hi Rob,
On Mon, Jul 19, 2010 at 3:10 AM, Rob Withers <reefedjib at yahoo.com> wrote:
Eliot,
I am getting a segmentation fault running Cog headless on linux. Here is the stack dump. Below is a second stack dump that looks different.
While the heap corruption might be a bug in Cog it might also be heap corruption from external code (e.g. objects passed through FFI calls to external code that overwrites those objects' bounds).
There's a leak checker in Cog (see the -leakcheck argument in platforms/unix/vm/sqUnixMain.c) that can help you localise this. Its best to distrust your code before you distrust the VM, simply because thinking it's the VM can blind-side you to potential bugs in your own code or other parts of the system. The goal here is a reproducible case. If you get a reproducible case that doesn't use any external code then the bug is in the VM.
HTH
Eliot
HTH,
Rob
FIRST STACK DUMP
vawhigso at vawhigs.org [~/public_html/squeakelib/Cog]# kill -USR1 30247
vawhigso at vawhigs.org [~/public_html/squeakelib/Cog]#
Received user signal, printing active stack:
0xff940ab8 I SmalltalkImage>garbageCollect -1207282732: a(n) SmalltalkImage
0xff940ad0 M Introducer class>areVatsRunning -1144872564: a(n) Introducer class
0xff940ae8 M PluggableButtonMorph>getModelState -1134952004: a(n) PluggableButtonMorph
0xff940b00 M PluggableButtonMorph>update: -1134952004: a(n) PluggableButtonMorph
0xff940b1c M StepMessage(MessageSend)>value -1134947088: a(n) StepMessage
0xff940b38 M StepMessage(MorphicAlarm)>value: -1134947088: a(n) StepMessage
0xff940b64 M WorldState>runLocalStepMethodsIn: -1215450852: a(n) WorldState
0xff940b90 M WorldState>runStepMethodsIn: -1215450852: a(n) WorldState
0xff940bac M PasteUpMorph>runStepMethods -1215450600: a(n) PasteUpMorph
0xff940bc8 M WorldState>doOneCycleNowFor: -1215450852: a(n) WorldState
0xff940be4 M WorldState>doOneCycleFor: -1215450852: a(n) WorldState
0xff940c00 M PasteUpMorph>doOneCycle -1215450600: a(n) PasteUpMorph
0xff940c20 I [] in Project class>spawnNewProcess -1138060792: a(n) Project class
-1133485544 s [] in
Segmentation fault
Smalltalk stack dump:
0xff940ab8 I SmalltalkImage>garbageCollect -1207282732: a(n) SmalltalkImage
0xff940ad0 M Introducer class>areVatsRunning -1144872564: a(n) Introducer class
0xff940ae8 M PluggableButtonMorph>getModelState -1134952004: a(n) PluggableButtonMorph
0xff940b00 M PluggableButtonMorph>update: -1134952004: a(n) PluggableButtonMorph
0xff940b1c M StepMessage(MessageSend)>value -1134947088: a(n) StepMessage
0xff940b38 M StepMessage(MorphicAlarm)>value: -1134947088: a(n) StepMessage
0xff940b64 M WorldState>runLocalStepMethodsIn: -1215450852: a(n) WorldState
0xff940b90 M WorldState>runStepMethodsIn: -1215450852: a(n) WorldState
0xff940bac M PasteUpMorph>runStepMethods -1215450600: a(n) PasteUpMorph
0xff940bc8 M WorldState>doOneCycleNowFor: -1215450852: a(n) WorldState
0xff940be4 M WorldState>doOneCycleFor: -1215450852: a(n) WorldState
0xff940c00 M PasteUpMorph>doOneCycle -1215450600: a(n) PasteUpMorph
0xff940c20 I [] in Project class>spawnNewProcess -1138060792: a(n) Project class
SECOND STACK DUMP
vawhigso at vawhigs.org [~/public_html/squeakelib/Cog]# kill -USR1 7340
Received user signal, printing active stack:
vawhigso at vawhigs.org [~/public_html/squeakelib/Cog]# 0xffaf3398 I SmalltalkImage>garbageCollect -1207897132: a(n) SmalltalkImage
0xffaf33b0 M Introducer class>areVatsRunning -1145486964: a(n) Introducer class
0xffaf33c8 M PluggableButtonMorph>getModelState -1135564980: a(n) PluggableButtonMorph
0xffaf33e0 M PluggableButtonMorph>update: -1135564980: a(n) PluggableButtonMorph
0xffaf33fc M StepMessage(MessageSend)>value -1135561416: a(n) StepMessage
0xffaf3418 M StepMessage(MorphicAlarm)>value: -1135561416: a(n) StepMessage
0xffaf3444 M WorldState>runLocalStepMethodsIn: -1216065252: a(n) WorldState
0xffaf3470 M WorldState>runStepMethodsIn: -1216065252: a(n) WorldState
0xffaf348c M PasteUpMorph>runStepMethods -1216065000: a(n) PasteUpMorph
0xffaf34a8 M WorldState>doOneCycleNowFor: -1216065252: a(n) WorldState
0xffaf34c4 M WorldState>doOneCycleFor: -1216065252: a(n) WorldState
0xffaf34e0 M PasteUpMorph>doOneCycle -1216065000: a(n) PasteUpMorph
0xffaf3500 I [] in Project class>spawnNewProcess -1138675192: a(n) Project class
-1134099944 s [] in BlockClosure>newProcess
Received user signal, printing all processes:
Process 0xbc670278 priority 40
0xffaf3398 I SmalltalkImage>garbageCollect -1207897132: a(n) SmalltalkImage
0xffaf33b0 M Introducer class>areVatsRunning -1145486964: a(n) Introducer class
0xffaf33c8 M PluggableButtonMorph>getModelState -1135564980: a(n) PluggableButtonMorph
0xffaf33e0 M PluggableButtonMorph>update: -1135564980: a(n) PluggableButtonMorph
0xffaf33fc M StepMessage(MessageSend)>value -1135561416: a(n) StepMessage
0xffaf3418 M StepMessage(MorphicAlarm)>value: -1135561416: a(n) StepMessage
0xffaf3444 M WorldState>runLocalStepMethodsIn: -1216065252: a(n) WorldState
0xffaf3470 M WorldState>runStepMethodsIn: -1216065252: a(n) WorldState
0xffaf348c M PasteUpMorph>runStepMethods -1216065000: a(n) PasteUpMorph
0xffaf34a8 M WorldState>doOneCycleNowFor: -1216065252: a(n) WorldState
0xffaf34c4 M WorldState>doOneCycleFor: -1216065252: a(n) WorldState
0xffaf34e0 M PasteUpMorph>doOneCycle -1216065000: a(n) PasteUpMorph
0xffaf3500 I [] in Project class>spawnNewProcess -1138675192: a(n) Project class
-1134099944 s [] in BlockClosure>newProcess
Process 0xbc97fc44 priority 50
0xffafa4c0 M WeakArray class>finalizationProcess -1210174624: a(n) WeakArray class
0xffafa4e0 I [] in WeakArray class>restartFinalizationProcess -1210174624: a(n) WeakArray class
0xffafa500 I [] in BlockClosure>newProcess -1130890396: a(n) BlockClosure
Process 0xb8125518 priority 80
widowed caller frame
EventualProcess 0xbbbd6e10 priority 60
-1134095516 s [] in Delay>wait
-1134049404 s BlockClosure>ifCurtailed:
-1134095648 s Delay>wait
-1134049312 s [] in VatTPManager class>finalizationLoop
-1145210696 s BlockClosure>repeat
-1145213336 s VatTPManager class>finalizationLoop
-1145213520 s [] in VatTPManager class>?
EventualProcess 0xbc5c9174 priority 30
-1134783048 s SharedQueue>next
-1134783140 s [] in Vat>processSends
-1134751716 s BlockClosure>ifCurtailed:
-1134783276 s Vat>processSends
-1134783984 s [] in EventualProcess>setupContext
Process 0xbc86c01c priority 60
0xffaf44c0 I RFBEventSensor(InputSensor)>userInterruptWatcher -1130865472: a(n) RFBEventSensor
0xffaf44e0 I [] in RFBEventSensor(InputSensor)>installInterruptWatcher -1130865472: a(n) RFBEventSensor
0xffaf4500 I [] in BlockClosure>newProcess -1132019908: a(n) BlockClosure
Process 0xbc86c1dc priority 60
widowed caller frame 8TŊĸ"Ļr·Zžð·ð·Zžð·ļ§r·TTŊĸōr·ĻZžZžÂž4Zžir·tTŊĸT·ÂžüYžÂžĀ\žð··TŊĸĶ·sZžðZžð·8·s·ĀTŊĸ(õq·$ZžĪ*îZžüYžÂžĀ\ž ]đ·
Process 0xbc86c3c8 priority 60
0xffaf74c0 I SmalltalkImage>lowSpaceWatcher -1207897132: a(n) SmalltalkImage
0xffaf74e0 I [] in SmalltalkImage>installLowSpaceWatcher -1207897132: a(n) SmalltalkImage
0xffaf7500 I [] in BlockClosure>newProcess -1132018968: a(n) BlockClosure
Process 0xbc985ef0 priority 60
widowed caller frame HÓŊĸúq·Ā\žð·ð·Ā\žð· úq·lÓŊĸ(õq·Ô\žĀ\žD\žļ·
Segmentation fault
Can't dump Smalltalk stack. Not in VM thread
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