rsize += (allocator->page_size - 1);
rsize &= -allocator->page_size;
g_assert_cmpint((allocator->start + rsize), <=, allocator->end);
rsize += (allocator->page_size - 1);
rsize &= -allocator->page_size;
g_assert_cmpint((allocator->start + rsize), <=, allocator->end);