Reported by Martin Doerr:

gc/shenandoah/TestElasticTLAB.java#generational
#  Internal Error (src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:695), pid=2948314, tid=2948983
#  assert(size % CardTable::card_size_in_words() == 0) failed: size must be multiple of card table size, was 258


This assertion was seen on linux aarch64 with the following stack snippet:
V  [libjvm.so+0x15795a0]  ShenandoahFreeSet::allocate_aligned_plab(unsigned long, ShenandoahAllocRequest&, ShenandoahHeapRegion*)+0x22c  (shenandoahFreeSet.cpp:695)
V  [libjvm.so+0x157c748]  ShenandoahFreeSet::try_allocate_in(ShenandoahHeapRegion*, ShenandoahAllocRequest&, bool&)+0x3e8  (shenandoahFreeSet.cpp:788)
V  [libjvm.so+0x157dac8]  ShenandoahFreeSet::allocate_old_with_affiliation(ShenandoahAffiliation, ShenandoahAllocRequest&, bool&)+0x404  (shenandoahFreeSet.cpp:432)
V  [libjvm.so+0x157f384]  ShenandoahFreeSet::allocate_single(ShenandoahAllocRequest&, bool&)+0xaf4  (shenandoahFreeSet.cpp:589)
V  [libjvm.so+0x15b533c]  ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest&, bool&, bool)+0xac  (shenandoahHeap.cpp:1440)
V  [libjvm.so+0x15b5940]  ShenandoahHeap::allocate_memory(ShenandoahAllocRequest&, bool)+0x50  (shenandoahHeap.cpp:1331)
V  [libjvm.so+0x15b654c]  ShenandoahHeap::allocate_from_plab_slow(Thread*, unsigned long, bool)+0x10c  (shenandoahHeap.cpp:1281)
V  [libjvm.so+0x372bd4]  ShenandoahHeap::try_evacuate_object(oop, Thread*, ShenandoahHeapRegion*, ShenandoahAffiliation)+0x1614  (shenandoahHeap.inline.hpp:306)
V  [libjvm.so+0x373c08]  ShenandoahHeap::evacuate_object(oop, Thread*)+0x7a8  (shenandoahHeap.inline.hpp:346)
V  [libjvm.so+0x1687dcc]  void ShenandoahEvacuateUpdateRootClosureBase<true, false>::do_oop_work<oop>(oop*)+0xcac  (shenandoahClosures.inline.hpp:156)
V  [libjvm.so+0x16880a8]  ShenandoahEvacuateUpdateRootClosureBase<true, false>::do_oop(oop*)+0x88  (shenandoahClosures.inline.hpp:122)
V  [libjvm.so+0xb355dc]  frame::oops_interpreted_do(OopClosure*, RegisterMap const*, bool) const [clone .part.0]+0x17c  (frame.cpp:909)
V  [libjvm.so+0x16fc784]  StackWatermarkFramesIterator::process_one(void*)+0x174  (stackWatermark.cpp:103)
V  [libjvm.so+0x16fce44]  StackWatermark::start_processing_impl(void*)+0xb4  (stackWatermark.cpp:217)
V  [libjvm.so+0x1686f38]  ShenandoahStackWatermark::start_processing_impl(void*)+0xa8  (shenandoahStackWatermark.cpp:118)