memblock: report failures when memblock_can_resize is not set

The callers of memblock_reserve() do not check the return value
presuming that memblock_reserve() always succeeds, but there are
cases where it may fail.

Having numerous memblock reservations at early boot where
memblock_can_resize is unset may exhaust the INIT_MEMBLOCK_REGIONS sized
memblock.reserved regions array and an attempt to double this array via
memblock_double_array() will fail and will return -1 to the caller.

When this happens the system crashes anyway, but it's hard to identify
the reason for the crash.

Add a panic message to memblock_double_array() to aid debugging of the
cases when too many regions are reserved before memblock can resize
memblock.reserved array.

Link: https://lore.kernel.org/linux-kernel/20230614131746.3670303-1-songshuaishuai@tinylab.org/Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
Link: https://lore.kernel.org/r/20230624032607.921173-1-songshuaishuai@tinylab.orgSigned-off-by: Mike Rapoport (IBM) <rppt@kernel.org>

mm/memblock.c

@@ -424,7 +424,7 @@ static int __init_memblock memblock_double_array(struct memblock_type *type,
 	 * of memory that aren't suitable for allocation
 	 */
 	if (!memblock_can_resize)
-		return -1;
+		panic("memblock: cannot resize %s array\n", type->name);
 
 	/* Calculate new doubled size */
 	old_size = type->max * sizeof(struct memblock_region);