RFR (S): 8025228: assert(new_entry->reserved_words() == vs_word_size) fails in nightly

[Mikael Gerdin]

Bengt,

On 09/24/2013 01:32 PM, Bengt Rutisson wrote:
>
> Hi everyone,
>
> Could I have a couple of reviews for this change?
>
> http://cr.openjdk.java.net/~brutisso/8025228/webrev.00/
>
> https://bugs.openjdk.java.net/browse/JDK-8025228
>
> We hit this assert in VirtualSpaceList::get_new_chunk() when we have an
> allocation that is larger than VirtualSpaceSize and that is not aligned
> with vm_allocation_granularity. The reason is that the VirtualSpace will
> grow with sizes aligned to vm_allocation_granularity but we we only
> guarantee that the sizes we want to grow with are page aligned. This
> means that we only hit this assert on platforms (Windows) where
> vm_allocation_granularity > vm_page_size.
>
> Since VirtualSpaceSize is vm_allocation_granularity aligned on all
> platforms we only hit the assert for allocations larger than that size
> due to this line:
>
> 1224           size_t grow_vs_words =
> 1225             MAX2((size_t)VirtualSpaceSize, aligned_expand_vs_by_words);
>
> The fix is to make sure that the grow_vs_words value is
> vm_allocation_granularity aligned and not just page size aligned.
>
>
> Testing:
>
> Added a unit test that fails this way on Windows before my fix:
>
> Running internal VM tests
> Running test: TestReservedSpace_test()
> Running test: TestReserveMemorySpecial_test()
> Running test: TestVirtualSpace_test()
> Running test: MetaspaceAux_test()
> # To suppress the following error report, specify this argument
> # after -XX: or in .hotspotrc:  SuppressErrorAt=\metaspace.cpp:1145
> #
> # A fatal error has been detected by the Java Runtime Environment:
> #
> #  Internal Error (...src\share\vm\memory\metaspace.cpp:1145), pid=220,
> tid=3352
> #  assert(vs_byte_size % os::vm_allocation_granularity() == 0) failed:
> Not aligned
>
> After my fix the test passes on all platforms.
>
> Ran the UTE test list vm.quick-pcl.testlist. All test pass.

Great!
Ship it!

>
> Thanks,
> Bengt
>