RFR: 8375747: ZGC: ZForwardingTest is unable to commit memory on Windows

[Joel Sikström]

On Wed, 28 Jan 2026 20:20:28 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> The ZForwardingTest gtest first reserves memory via the ZGC APIs to do so and then uses the generic `os::commit_memory(...)` to commit the memory. That is problematic on Windows because the two APIs are not compatible there. I've updated the test to use ZGC's APIs to commit and map memory instead.
> 
> Thanks to @roberttoyonaga for finding this and helping out diagnosing this issue!
> 
> The patch also adds some tiny fixes to the assert code that mislead me while prototyping this.
> 
> I'll run this through tier1 testing.

test/hotspot/gtest/gc/z/zunittest.hpp line 140:

> 138: 
> 139:       char* mem = (char*)os::malloc(sizeof(ZPhysicalMemoryBacking), mtTest);
> 140:       _backing = new (mem) ZPhysicalMemoryBacking(max_capacity);

Should we call `create_backing` here instead?

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PR Review Comment: https://git.openjdk.org/jdk/pull/29471#discussion_r2738536027