memblock_bottom_up
if (memblock_bottom_up()) {
bool prev_bottom_up = memblock_bottom_up();
if (!memblock_bottom_up() && limit >= SZ_4G + size) {
if (memblock_bottom_up())
ASSERT_EQ(memblock_bottom_up(), memblock.bottom_up);
ASSERT_EQ(memblock_bottom_up(), false);
ASSERT_EQ(memblock_bottom_up(), memblock.bottom_up);
ASSERT_EQ(memblock_bottom_up(), true);