RFR: 8341491: Reserve and commit memory operations should be protected by NMT lock

[Robert Toyonaga]

On Tue, 25 Mar 2025 18:55:56 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> ... swapping the order of the release and NMT release booking as a way to shrink the lock scope for the release operation:
...
As long as we hold the reservation, no other thread can re-reserve the reservation, so Thread B can take its time to first perform the NMT release booking under the lock, and then perform the release without the lock.

Hi @stefank, I think that's true. But if the release/uncommit does not complete successfully we would need to readjust the accounting afterward. To do that we would need to retrieve the original memtag (at least for reserved regions) and potentially need to retrieve the original callsite data (if we're in detailed mode).

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

PR Comment: https://git.openjdk.org/jdk/pull/24084#issuecomment-2752423849