JDK-8306767 : Concurrent repacking of extra data in MethodData is potentially unsafe
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 11,17,20,21,22,23
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2023-04-24
  • Updated: 2024-02-01
  • Resolved: 2024-01-25
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JDK 23
23 b08Fixed
Related Reports
Relates :  
JDK-8215889 - assert(!_unloading) failed: This oop is not available to unloading class loader data with ZGC
Relates :  
JDK-8324129 - C2: Remove some ttyLocker usages in preparation for JDK-8306767
Relates :  
JDK-8231501 - VM crash in MethodData::clean_extra_data(CleanExtraDataClosure*): fatal error: unexpected tag 99
Description
See https://github.com/openjdk/jdk/pull/11996#issuecomment-1409331760 If any thread can potentially repack the extra data section then any code path which might receive data from the extra data section must guard against this by holding the lock.  JVMCI in general isn't exposed to this problem since it doesn't create speculative trap data entries.  It's probably likely to be exceeding rare since I guess this only occurs with ZGC.
Comments
Changeset: 746a0868 Author: Emanuel Peter <epeter@openjdk.org> Date: 2024-01-25 15:50:33 +0000 URL: https://git.openjdk.org/jdk/commit/746a08686bfad629fe045a762ed2fbb209763f6b
25-01-2024
A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/16840 Date: 2023-11-28 06:23:29 +0000
28-11-2023
Moving this to JDK 22 for now. Please update the fix version if a patch is ready in time for JDK 21.
03-05-2023
ILW = Unsafe repacking of extra data due to missing extra_data_lock, rare, no workaround = MLH = P4
25-04-2023