for (prev = NULL, cur = pool->extents; cur; prev = cur, cur = cur->next) {
if (addr >= cur->start
&& addr < PTR_ADD(cur->start, pool->size))
for (prev = NULL, cur = pool->extents; cur; prev = cur, cur = cur->next) {
if (addr >= cur->start
&& addr < PTR_ADD(cur->start, pool->size))