RFR: 8169931: 8k class metaspace chunks misallocated from 4k chunk freelist

Mikael Gerdin mikael.gerdin at oracle.com
Tue Nov 22 16:08:24 UTC 2016

Hi Stefan,

On 2016-11-22 15:54, Stefan Karlsson wrote:
> Hi all,
> Please, review this patch to fix a bug in ChunkManager::list_index():
>  http://cr.openjdk.java.net/~stefank/8169931/webrev.01

The change looks good to me.


> There's a great description of the bug in the bug report:
>  https://bugs.openjdk.java.net/browse/JDK-8169931
> There are two conceptual parts of the metaspace. The _class_ metaspace,
> and the _non-class_ metaspace. They have different chunk sizes, and
> while querying for the list index of a humongous chunk in the class
> metaspace, the code accidentally matched the size against the
> MediumChunk size of the non-class metaspace.
> I've changed the code to not query against the global ChunkSizes enum,
> but rather the values stored inside the ChunkManager instances.
> Therefore, the list_index() function was changed into an instance method.
> I've written a unit test that provoked the bug. It's a simplified test
> with vm asserts instead of gtest asserts. The reason is that the
> ChunkManager class is currently located in metaspace.cpp, and is not
> accessible from the gtest unit tests.
> Testing: jprt, Kitchensink, parallel class loading tests
> Thanks,
> StefanK

More information about the hotspot-dev mailing list