RFR: 8360048: NMT crash in gtest/NMTGtests.java: fatal error: NMT corruption: Block at 0x0000017748307120: header canary broken

[Afshin Zafari]

The canary header test failed since there were concurrent `remove` and `free()` from the tree. The `remove` operations are synch'ed with corresponding NMT lock. The `ReserveMemory::reserve()` uses the same lock internally and is not included in the locked code block.

Tests: tier5 {macosx-aarch64, linux-x64, windows-x64} x {debug, release}

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Commit messages:
 - 8360048: NMT crash in gtest/NMTGtests.java: fatal error: NMT corruption: Block at 0x0000017748307120: header canary broken

Changes: https://git.openjdk.org/jdk/pull/25950/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25950&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8360048
  Stats: 27 lines in 1 file changed: 19 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/25950.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25950/head:pull/25950

PR: https://git.openjdk.org/jdk/pull/25950