PGA_REQUEUE_HEAD
if ((old->flags & PGA_REQUEUE_HEAD) != 0) {
new.flags &= ~(PGA_REQUEUE | PGA_REQUEUE_HEAD);
KASSERT(nflag == PGA_REQUEUE || nflag == PGA_REQUEUE_HEAD,
vm_page_mvqueue(m, PQ_INACTIVE, PGA_REQUEUE_HEAD);
nflag = PGA_REQUEUE_HEAD;
if (nflag != PGA_REQUEUE_HEAD && old.queue == PQ_ACTIVE &&
#define PGA_QUEUE_OP_MASK (PGA_DEQUEUE | PGA_REQUEUE | PGA_REQUEUE_HEAD)
KASSERT(new.queue == PQ_INACTIVE || (new.flags & PGA_REQUEUE_HEAD) == 0,