RFR(S) 8205105: VM crashes with "assert(Universe::heap()->is_in_reserved(start + words - 1)) failed: not in heap

[Vladimir Kozlov]

On 6/20/18 4:17 PM, Igor Veresov wrote:
> 
> 
>> On Jun 20, 2018, at 3:43 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>
>> On 6/20/18 3:22 PM, Igor Veresov wrote:
>>>> On Jun 20, 2018, at 3:20 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>>>
>>>> Why Graal is affected even when LOHP is not used?
>>> LOHP is dynamically turned on by JVMTI.
>>
>> Okay. In other world we can't use fast TLAB refill because JVMTI can switch on LOHP at any time. Got it.
>>
> 
> Well, unless we want to add an additional dynamic check of the LOHP state. That’s also a possible solution if we want to keep the fast TLAB refill.

Nope. We removed it from Hotspot in JDK 11. I don't think we should 
spend time supporting it in Graal.

> 
>> I still did not get why GC tests which do not use LOHP still fail with Graal. And how these changes fix it?
> 
> Because, as Stefan noted in the bug, when Graal does fast TLAB refill it does so without setting the new _allocation_end field.

It means Graal uses fast TLAB refill by default. That is answer I was 
waiting for.

> The changes fix it by avoiding manually allocating TLABs in the stub (during fast TLAB refill) and calling the runtime instead.

Okay. Got it. Reviewed.

Thanks,
Vladimir

> 
> igor
> 
>>
>> Thanks,
>> Vladimir
>>
>>>>
>>>> I don't see changes which mapped new TLAB fields added by Low-Overhead Heap Profiling.
>>>>
>>>> I don't see your answers to Stefan's comment in bug report about Graal's code which is not fixed for _allocation_end.
>>>>
>>>> Does Graal still use fast TLAB refill as default mode?
>>> You cannot use TLAB refill with LOHP at all.
>>>>
>>>> FastTLABRefill was deprecated by 8194084: "Obsolete FastTLABRefill and remove the related code":
>>>>
>>>> http://hg.openjdk.java.net/jdk/jdk/rev/9010e596f391
>>>>
>>>> Should we remove it from Graal too?
>>>>
>>> Not for JDKs <11.
>>> igor
>>>> Thanks,
>>>> Vladimir
>>>>
>>>> On 6/20/18 2:47 PM, Igor Veresov wrote:
>>>>> Low-Overhead Heap Profiling is not compatible with fast TLAB refill. It needs to be disabled.
>>>>> Webrev: http://cr.openjdk.java.net/~iveresov/8205105/webrev/
>>>>> Thanks,
>>>>> igor
>