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  1. JDK
  2. JDK-8235982

AArch64: Insufficient memory barriers in shadow region algorithm

    Details

    • Subcomponent:
      gc
    • Resolved In Build:
      b28
    • CPU:
      aarch64

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        Description

        I occasionally see this test crash on AArch64 with the following assertion failure:

        # Internal Error (/home/ent-user/ci-scripts/jdk_src/src/hotspot/share/oops/compressedOops.inline.hpp:84), pid=85650, tid=85656
        # assert(!is_null(v)) failed: narrow klass value can never be zero

        See the attached full crash log.

        Looks like there's a missing store-store barrier in parallal GC MoveAndUpdateShadowClosure::complete_region, as the stores from set_shadow_region() and mark_filled() can be reordered on a non-TSO processor.

        I'll do some more testing and send out a patch.

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                • Assignee:
                  ngasson Nick Gasson
                  Reporter:
                  ngasson Nick Gasson
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                  • Created:
                    Updated:
                    Resolved: