RFR (XS): 8023037 : Race between ciEnv::register_method and nmethod::make_not_entrant_or_zombie

[Vladimir Kozlov]

Should be

http://cr.openjdk.java.net/~vlivanov/8023037/webrev.01/

What about this place:

src/cpu/sparc/vm/sharedRuntime_sparc.cpp:  if (StressNonEntrant) {

Vladimir

On 11/5/13 11:10 AM, Vladimir Ivanov wrote:
> Updated fix:
> http://cr.openjdk.java.net/~vlivanov/8023037/webrev.00/
>
> Removed broken StressNonEntrant code.
> Updated comments.
>
> Best regards,
> Vladimir Ivanov
>
> On 11/5/13 3:39 PM, Vladimir Ivanov wrote:
>> http://cr.openjdk.java.net/~vlivanov/8023037/webrev.00/
>>
>> There's a race between compiler thread during method registration and
>> sweeper: sweeper can invalidate a nmethod which hasn't been installed
>> yet.
>>
>> Consider the following scenario:
>>    ciEnv::register_method:
>>      - new nmethod(...)
>>
>>    sweeper:
>>      - invalidates newly allocated nmethod and patches VEP to call
>> handle_wrong_method
>>      - tries to unlink it, but method()->from_compiled_entry() !=
>> verified_entry_point() since nmethod hasn't been installed yet
>>
>>    ciEnv::register_method:
>>      - installs already invalidated nmethod
>>
>> Calling corresponding Java method will lead to infinite loop: VEP of the
>> compiled method calls handle_wrong_method and call site resolution
>> returns the very same compiled method.
>>
>> The fix is to grab a lock after nmethod is allocated in the code cache
>> and check that it hasn't been already invalidated by the sweeper before
>> proceeding. Sweeper already synchronizes on a nmethod before
>> invalidating it.
>>
>> Testing: failing test w/ diagnostic output.
>>
>> Thanks!
>>
>> Best regards,
>> Vladimir Ivanov