Dave reported big numa system booting is broken.

It turns out that commit 5b6e5295 ("x86: memblock: set current limit
to max low memory address") sets the limit to low wrongly.

max_low_pfn_mapped is different from max_pfn_mapped.
max_low_pfn_mapped is always under 4G.

That will memblock_alloc_nid all go under 4G.

Revert 5b6e5295 to fix a no-boot regression which was triggered by
457ff1de ("lib/swiotlb.c: use memblock apis for early memory
allocations").
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Reported-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>