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

[Tom Rodriguez]

Looks good.

tom

On Jun 22, 2010, at 12:02 PM, Vladimir Kozlov wrote:

> Thank you, Tom and Paul
> 
> I updated webrev
> 
> http://cr.openjdk.java.net/~kvn/6947341/webrev.02
> 
> Vladimir
> 
> 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:
>>>>>>> http://cr.openjdk.java.net/~kvn/6947341/webrev
>>>>>>> 
>>>>>>> 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.
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>