RFR: 8329757: Crash with fatal error: DEBUG MESSAGE: Fast Unlock lock on stack [v2]

Axel Boldt-Christmas aboldtch at openjdk.org
Thu Apr 11 05:37:05 UTC 2024


> `Deoptimization::relock_objects` may reorder locks within in the `LockStack` which are added inside the same vframe. This can be handled by the interpreter but if OSR has occurred C2 may observe this invalid order in the `LockStack`, which breaks its assumption leading to incorrect behaviour.
> 
> This patch functionally makes sure that the LockStack is always consistent by always inflating eliminated locks when `Deoptimization::relock_objects`  is called.
> 
> It also adds verification code which checks that the LockStack is consistent with the lock order observed inside the deoptimized vframes. 
> 
> Note: for leaf deoptimizations we have enough information to recreate a correct top of the LockStack with minimal inflations, however that should be a separate RFE. This only inflates eliminated locks so the worth of solving that may be minimal or even detrimental. 
> 
> Tests still running. Tier 1-5 done, Tier 6-7 running.

Axel Boldt-Christmas has updated the pull request incrementally with three additional commits since the last revision:

 - Drop includes
 - Strengthen waiting_monitor assert
 - Add explicit break

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18715/files
  - new: https://git.openjdk.org/jdk/pull/18715/files/e11d9b04..d2e8216d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18715&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18715&range=00-01

  Stats: 4 lines in 2 files changed: 1 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18715.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18715/head:pull/18715

PR: https://git.openjdk.org/jdk/pull/18715


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