RFR: 8324174: assert(m->is_entered(current)) failed: invariant

[Emanuel Peter]

On Fri, 26 Jan 2024 22:09:27 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> When we fail re-allocate scalarized object during deoptimization we unlock all monitors in affected frames and throw OOM exception [JDK-6898462](https://bugs.openjdk.org/browse/JDK-6898462).
> The unlocking was done in incorrect order starting from outermost monitor which cause this assert when we unlock following nested monitor (the same object) - it sees that it was already unlocked.
> 
> The fix is to start unlocking from most nested/inner monitor.
> I also noticed that we have incorrect order of frames for re-locking during deoptimization. We should start from outermost frame. Inside frame re-locking order is correct - from outermost monitor.
> 
> Added regression test with deep nested locks.
> Ran tier1-5, Xcomp, stress testing.

src/hotspot/share/runtime/deoptimization.cpp line 395:

> 393: #endif // !PRODUCT
> 394:   // Start locking from outermost/oldest frame
> 395:   for (int i = (chunk->length() - 1); i >= 0 ; i--) {

Suggestion:

  for (int i = (chunk->length() - 1); i >= 0; i--) {

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PR Review Comment: https://git.openjdk.org/jdk/pull/17600#discussion_r1471641008