MIN_PBL_SHIFT
rdev->stats.pbl.cur += roundup(size, 1 << MIN_PBL_SHIFT);
rdev->stats.pbl.cur -= roundup(size, 1 << MIN_PBL_SHIFT);
if (vmem_xalloc(sc->pbl_arena, roundup(size, (1 << MIN_PBL_SHIFT)),
vmem_xfree(sc->pbl_arena, addr, roundup(size, (1 << MIN_PBL_SHIFT)));