> On some macosx-aarch64 systems, not all mapped pages are dumped to the core 
> file. This first turned up with 
> [JDK-8293563](https://bugs.openjdk.org/browse/JDK-8293563) where large parts 
> of the ZGC heap would not be in the core file, leading to various SA address 
> errors. For JDK-8293563 the issue was addressed by having the core file test 
> always use `-XX:+AlwaysPreTouch` on macosx-aarch64. This seemed to force the 
> ZGC pages to always end up in the core file.
> 
> A similar issue has been noticed with mapped in pages of the CDS archive. We 
> are seeing cases where SA references to addresses that are clearly in the CDS 
> archive (based on info in the hs_err file) are failing to be read from the 
> core file by SA. This problem has turned up a number of times during CI 
> testing, but I have yet to be able to reproduce it myself. This PR is an 
> attempt to address this testing issue by having the CDS archive also pretouch 
> all mapped in pages when `-XX:+AlwaysPreTouch` is used.
> 
> Tested with tier1 and tier3 and also ran the test about 5,000 times with and 
> without the fix. It never reproduced for either. Hopefully the problem is 
> gone with this fix, but it may take a few months of CI testing before we can 
> be confident it is fixed.

Chris Plummer has updated the pull request incrementally with one additional 
commit since the last revision:

  Minor cleanup based on review suggestions

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15423/files
  - new: https://git.openjdk.org/jdk/pull/15423/files/72b6fbcd..2dabe4e7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15423&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15423&range=00-01

  Stats: 6 lines in 1 file changed: 1 ins; 3 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15423.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15423/head:pull/15423

PR: https://git.openjdk.org/jdk/pull/15423

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