RFR: JDK-8265298: Hard VM crash when deadlock between "access" and higher ranked lock is detected

Aleksey Shipilev shade at openjdk.java.net
Thu Apr 15 17:13:02 UTC 2021


I stumbled upon this when doing some Shenandoah work. The development code tried to lock the `leaf` lock, while already holding the `access` lock. Normally it would have been detected by VM, but instead, we tried to recursively acquire `tty_lock` for `Thread::print_owned_locks`. But that `tty` lock is still ranked higher than `access`, so deadlock detection triggers over and over again until we run out of stack and crash hard. `tty` and `access` are ranked this way because of [JDK-8214315](https://bugs.openjdk.java.net/browse/JDK-8214315). Read the rest in the bug.  

I believe the way out is to only enter `Thread::print_owned_locks` when we know deadlock detection code would not run in circles. New test for `access` and `leaf` shows the original failure. Another new test checks `tty` and `special` to verify that the check should be `> tty`, not `>= tty`.

Additional testing:
 - [ ] Linux x86_64 fastdebug tier1
 - [x] New regression tests (fail without the patch, pass wit it)

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

Commit messages:
 - JDK-8265298: Hard VM crash when deadlock between "access" and higher ranked lock is detected

Changes: https://git.openjdk.java.net/jdk/pull/3524/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3524&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265298
  Stats: 68 lines in 2 files changed: 67 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3524.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3524/head:pull/3524

PR: https://git.openjdk.java.net/jdk/pull/3524


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