x86: revert wrong memblock current limit setting

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: NYinghai Lu <yinghai@kernel.org>
Reported-by: NDave Hansen <dave.hansen@intel.com>
Acked-by: NSantosh 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/page_types.h

@@ -51,9 +51,9 @@ extern int devmem_is_allowed(unsigned long pagenr);
 extern unsigned long max_low_pfn_mapped;
 extern unsigned long max_pfn_mapped;
 
-static inline phys_addr_t get_max_low_mapped(void)
+static inline phys_addr_t get_max_mapped(void)
 {
-	return (phys_addr_t)max_low_pfn_mapped << PAGE_SHIFT;
+	return (phys_addr_t)max_pfn_mapped << PAGE_SHIFT;
 }
 
 bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn);

arch/x86/kernel/setup.c

@@ -1119,7 +1119,7 @@ void __init setup_arch(char **cmdline_p)
 
 	setup_real_mode();
 
-	memblock_set_current_limit(get_max_low_mapped());
+	memblock_set_current_limit(get_max_mapped());
 	dma_contiguous_reserve(0);
 
 	/*