Line-accurate confirmation (runtime demo skipped: vm.swapcache data
caching is off by default and enabling swapcaching on the audit
guest risks wedging it for a Info-tier item):
sys/vm/vm_swapcache.c:457-462  anchor scan skips VREG pages with
   PG_NOTMETA set ('PG_NOTMETA generically means do not swapcache
   this' - HAMMER sets it for regular data buffers)
sys/vm/vm_swapcache.c:608 and :628  both cluster loops gate only on
   isblkdev:  if (isblkdev && (m->flags & PG_NOTMETA)) break;
-> a VREG anchor can cluster up to 31 adjacent PG_NOTMETA data pages
into swap_pager_putpages, assigning swap backing in violation of the
flag. No memory-safety impact; requires data_enable.