Request for reviews (M): 6947341: JVM Crash running Oracle ATG CRMDemo

Vladimir Kozlov vladimir.kozlov at
Tue Jun 22 12:02:18 PDT 2010

Thank you, Tom and Paul

I updated webrev


Tom Rodriguez wrote:
> Ok.  Sounds good.
> tom
> On Jun 22, 2010, at 11:05 AM, Vladimir Kozlov wrote:
>> Tom Rodriguez wrote:
>>>>> Why does one of the cases return instead of falling through as if the allocation failed?
>>>> Because if it did not return it will fall into next code which will do regular allocation (without large pages). I want it to return so an other attempt could be made with different requested address and with large pages.
>>> How do you guarantee that it will terminate successfully?
>> There are only 2 attempts to allocate at the requested address. If they fail the requested_address is set to NULL and this new code will not be executed.
>> Vladimir
>>> tom
>>>> Vladimir
>>>>> tom
>>>>> On Jun 22, 2010, at 8:46 AM, Vladimir Kozlov wrote:
>>>>>> Fixed 6947341: JVM Crash running Oracle ATG CRMDemo
>>>>>> Missing protected page below heap with compressed oops
>>>>>> which use narrow_oop_base and implicit null check.
>>>>>> It is caused by ReservedSpace code misses checks that OS
>>>>>> reserved heap at requested address.
>>>>>> Before 6951686 fix Linux will reserve heap memory at address
>>>>>> which is not requested for compressed oops VM (usually above
>>>>>> 32Gb virtual address: 0x00002aaaae200000). But VM thinks
>>>>>> it did reserve at requested address and it does not need
>>>>>> protected page below heap, so the code in protect_noaccess_prefix()
>>>>>> is not executed.
>>>>>> Solution:
>>>>>> Add missing checks. I also added few asserts and prints
>>>>>> to make sure memory reservation done correctly for
>>>>>> compressed oops.
>>>>>> Verified with CRMDemo.

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