RFA: 8208091: SA: jhsdb jstack --mixed throws UnmappedAddressException on i686

[Rob McKenna]

Hi Severin,

Not totally comfortable with the lack of a test, but I do see why.
Approved.

    -Rob

On 10/10/18 17:03, Severin Gehwolf wrote:
> Hi,
> 
> Please approve this 8u packport of JDK-8208091. In JDK 12 the command
> to trigger the bug is "jhsdb jstack --mixed". In JDK 8u the command is
> "jstack -m". The bug is the same, though. The actual fix is the same as
> in JDK 12 post path-unshuffeling.
> 
> The testing infrastructure is rather different in JDK 8. There are
> hardly any serviceability tests. In order to keep changes to a stable
> release minimal the JDK 8u patch only inludes the fix. The test isn't
> 100% guaranteed to trigger the problem anyway. Thoughts?
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8208091
> JDK 8 patch: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/JDK-8208091.jdk8.export.patch
> JDK 12 change: http://hg.openjdk.java.net/jdk/jdk/rev/2e98c7737d8f
> 
> Thanks,
> Severin
> 
> Prior the fix:
> 
> # ./jdk-8u-prior-jstack-fix/bin/jstack -m 2339
> Attaching to process ID 2339, please wait...
> Debugger attached successfully.
> Server compiler detected.
> JVM version is 25.71-b00
> Deadlock Detection:
> 
> No deadlocks found.
> 
> ----------------- 2340 -----------------
> 0xf7755430		????????
> ----------------- 2341 -----------------
> 0xf7755430		????????
> ----------------- 2342 -----------------
> 0xf7755430		????????
> ----------------- 2343 -----------------
> 0xf7755430		????????
> ----------------- 2344 -----------------
> 0xf7755430		????????
> ----------------- 2345 -----------------
> 0xf7755430		????????
> ----------------- 2346 -----------------
> 0xf7755430		????????
> ----------------- 2347 -----------------
> 0xf7755430		????????
> sun.jvm.hotspot.debugger.UnmappedAddressException: f0
> 	at sun.jvm.hotspot.debugger.PageCache.checkPage(PageCache.java:208)
> 	at sun.jvm.hotspot.debugger.PageCache.getData(PageCache.java:63)
> 	at sun.jvm.hotspot.debugger.DebuggerBase.readBytes(DebuggerBase.java:225)
> 	at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.readCInteger(LinuxDebuggerLocal.java:498)
> 	at sun.jvm.hotspot.debugger.DebuggerBase.readAddressValue(DebuggerBase.java:462)
> 	at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.readAddress(LinuxDebuggerLocal.java:433)
> 	at sun.jvm.hotspot.debugger.linux.LinuxAddress.getAddressAt(LinuxAddress.java:74)
> 	at sun.jvm.hotspot.debugger.linux.x86.LinuxX86CFrame.sender(LinuxX86CFrame.java:69)
> 	at sun.jvm.hotspot.tools.PStack.run(PStack.java:161)
> 	at sun.jvm.hotspot.tools.PStack.run(PStack.java:58)
> 	at sun.jvm.hotspot.tools.PStack.run(PStack.java:53)
> 	at sun.jvm.hotspot.tools.JStack.run(JStack.java:66)
> 	at sun.jvm.hotspot.tools.Tool.startInternal(Tool.java:260)
> 	at sun.jvm.hotspot.tools.Tool.start(Tool.java:223)
> 	at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
> 	at sun.jvm.hotspot.tools.JStack.main(JStack.java:92)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> 	at java.lang.reflect.Method.invoke(Method.java:498)
> 	at sun.tools.jstack.JStack.runJStackTool(JStack.java:140)
> 	at sun.tools.jstack.JStack.main(JStack.java:106)
> ----------------- 2348 -----------------
> 0xf7755430		????????
> ----------------- 2349 -----------------
> 0xf7755430		????????
> ----------------- 2350 -----------------
> 0xf7755430		????????
> ----------------- 2351 -----------------
> 0xf7755430		????????
> ----------------- 2339 -----------------
> 0xf7755430		????????
> 
> Post fix:
> 
> $ ./jdk-8u-post-jstack-fix/bin/jstack -m 2339
> Attaching to process ID 2339, please wait...
> Debugger attached successfully.
> Server compiler detected.
> JVM version is 25.71-b00
> Deadlock Detection:
> 
> No deadlocks found.
> 
> ----------------- 2340 -----------------
> 0xf7755430		????????
> ----------------- 2341 -----------------
> 0xf7755430		????????
> ----------------- 2342 -----------------
> 0xf7755430		????????
> ----------------- 2343 -----------------
> 0xf7755430		????????
> ----------------- 2344 -----------------
> 0xf7755430		????????
> ----------------- 2345 -----------------
> 0xf7755430		????????
> ----------------- 2346 -----------------
> 0xf7755430		????????
> ----------------- 2347 -----------------
> 0xf7755430		????????
> ----------------- 2348 -----------------
> 0xf7755430		????????
> ----------------- 2349 -----------------
> 0xf7755430		????????
> ----------------- 2350 -----------------
> 0xf7755430		????????
> ----------------- 2351 -----------------
> 0xf7755430		????????
> ----------------- 2339 -----------------
> 0xf7755430		????????
>