x86/mm: Fix zone ranges boot printout

This is the usual physical memory layout boot printout:
...
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x00001000-0x00ffffff]
[ 0.000000] DMA32 [mem 0x01000000-0xffffffff]
[ 0.000000] Normal [mem 0x100000000-0xc3fffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x00001000-0x00099fff]
[ 0.000000] node 0: [mem 0x00100000-0xbf78ffff]
[ 0.000000] node 0: [mem 0x100000000-0x63fffffff]
[ 0.000000] node 1: [mem 0x640000000-0xc3fffffff]
...

This is the log when we set "mem=2G" on the boot cmdline:
...
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x00001000-0x00ffffff]
[ 0.000000] DMA32 [mem 0x01000000-0xffffffff] // should be 0x7fffffff, right?
[ 0.000000] Normal empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x00001000-0x00099fff]
[ 0.000000] node 0: [mem 0x00100000-0x7fffffff]
...

This patch fixes the printout, the following log shows the right
ranges:
...
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x00001000-0x00ffffff]
[ 0.000000] DMA32 [mem 0x01000000-0x7fffffff]
[ 0.000000] Normal empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x00001000-0x00099fff]
[ 0.000000] node 0: [mem 0x00100000-0x7fffffff]
...

Suggested-by: Andrew Morton <[e-mail]>
Signed-off-by: Xishi Qiu <[e-mail]>
Cc: Linux MM <[e-mail]>
Cc: <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/dma.h

···
 #define MAX_DMA_CHANNELS	8
 
 /* 16MB ISA DMA zone */
-#define MAX_DMA_PFN   ((16 * 1024 * 1024) >> PAGE_SHIFT)
+#define MAX_DMA_PFN   ((16UL * 1024 * 1024) >> PAGE_SHIFT)
 
 /* 4GB broken PCI/AGP hardware bus master zone */
 #define MAX_DMA32_PFN ((4UL * 1024 * 1024 * 1024) >> PAGE_SHIFT)

arch/x86/mm/init.c

···
 	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 
 #ifdef CONFIG_ZONE_DMA
-	max_zone_pfns[ZONE_DMA]		= MAX_DMA_PFN;
+	max_zone_pfns[ZONE_DMA]		= min(MAX_DMA_PFN, max_low_pfn);
 #endif
 #ifdef CONFIG_ZONE_DMA32
-	max_zone_pfns[ZONE_DMA32]	= MAX_DMA32_PFN;
+	max_zone_pfns[ZONE_DMA32]	= min(MAX_DMA32_PFN, max_low_pfn);
 #endif
 	max_zone_pfns[ZONE_NORMAL]	= max_low_pfn;
 #ifdef CONFIG_HIGHMEM