Thanks for information. Yeah, that makes somewhat more sense. Can you ever see the failure if you disable CONFIG_TRANSPARENT_HUGEPAGE?
HAVE_ARCH_TRANSPARENT_HUGEPAGE [=n] Seems there is no THP on alpha.
Because your findings still seem to indicate that there' some problem with page migration and Alpha (added MM list to CC).
But my kernel config had memory compaction (that turned on page migration) and bounce buffers. I do not remember why I found them necessary but I will try without them. -- Meelis Roos <mroos@xxxxxxxx>