[PATCH] x86: fix nodes_cover_memory

[Yinghai Lu <yinghai@kernel.org>]

found one system that missed one entry for one node in SRAT, and that SRAT is not
rejected by nodes_cover_memory()

it turns out that we can not use absent_page_in_range to calaulate
e820ram, bacause that will use early_node_map and that is AND result of
e820 and SRAT.

revert back to use e820_hole_size instead.

also change that difference checking to 1M instead of 4G,
because e820ram, and pxmram are in pages.

[ Impact: reject wrong SRAT tables ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>

---
 arch/x86/mm/srat_64.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/mm/srat_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/srat_64.c
+++ linux-2.6/arch/x86/mm/srat_64.c
@@ -345,9 +345,9 @@ static int __init nodes_cover_memory(con
 			pxmram = 0;
 	}
 
-	e820ram = max_pfn - absent_pages_in_range(0, max_pfn);
+	e820ram = max_pfn - (e820_hole_size(0, max_pfn<<PAGE_SHIFT)>>PAGE_SHIFT);
 	/* We seem to lose 3 pages somewhere. Allow a bit of slack. */
-	if ((long)(e820ram - pxmram) >= 1*1024*1024) {
+	if ((long)(e820ram - pxmram) >= (1<<(20 - PAGE_SHIFT))) {
 		printk(KERN_ERR
 	"SRAT: PXMs only cover %luMB of your %luMB e820 RAM. Not used.\n",
 			(pxmram << PAGE_SHIFT) >> 20,