Add 129th region into the memblock, and this will trigger the
memblock_double_array() function, this needs valid memory regions. So
using dummy_physical_memory_init() to allocate a large enough memory
region, and split it into a large enough memory which can be choosed by
memblock_double_array(), and the left memory will be split into small
memory region, and add them into the memblock. It make sure the
memblock_double_array() will always choose the valid memory region that
is allocated by the dummy_physical_memory_init().
So memblock_double_array() must success.

Another thing should be done is to restore the memory.regions after
memblock_double_array(), due to now the memory.regions is pointing to a
memory region allocated by dummy_physical_memory_init(). And it will
affect the subsequent tests if we don't restore the memory region. So
simply record the origin region, and restore it after the test.
Signed-off-by: Shaoqin Huang <shaoqin.huang@intel.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Link: https://lore.kernel.org/r/20221011062128.49359-2-shaoqin.huang@intel.com