RFR: 8328944: NMT reports "unknown" memory [v2]

[Gerard Ziemski]

On Wed, 20 Nov 2024 15:34:42 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> Gerard Ziemski has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>> 
>>  - avoid using mtNone
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8328944
>>  - revert, we will re-do with a smaller change
>>  - remove more mtNone
>>  - remove API that allows to change the mem_tag for virtual memory, feedback
>>  - do not allow default parameter for mtNone
>
> src/hotspot/share/memory/virtualspace.hpp line 74:
> 
>> 72:   // Initialize the reserved space with the given size. Depending on the size
>> 73:   // a suitable page size and alignment will be used.
>> 74:   explicit ReservedSpace(size_t size, MemTag mem_tag);
> 
> Suggestion:
> 
>   ReservedSpace(size_t size, MemTag mem_tag);
> 
> No need for `explicit` when you've added a parameter.

Fixed.

> src/hotspot/share/runtime/safepointMechanism.cpp line 61:
> 
>> 59:     const size_t page_size = os::vm_page_size();
>> 60:     const size_t allocation_size = 2 * page_size;
>> 61:     char* polling_page = os::reserve_memory(allocation_size, false, mtSafepoint);
> 
> Suggestion:
> 
>     char* polling_page = os::reserve_memory(allocation_size, !ExecMem, mtSafepoint);

Fixed.

> src/hotspot/share/utilities/debug.cpp line 712:
> 
>> 710: 
>> 711: void initialize_assert_poison() {
>> 712:   char* page = os::reserve_memory(os::vm_page_size(), false, mtInternal);
> 
> Suggestion:
> 
>   char* page = os::reserve_memory(os::vm_page_size(), !ExecMem, mtTest);

Fixed.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/21843#discussion_r1852621576
PR Review Comment: https://git.openjdk.org/jdk/pull/21843#discussion_r1852622931
PR Review Comment: https://git.openjdk.org/jdk/pull/21843#discussion_r1852622511