[PATCH] x86_64: Don't try to put kernel page tables beyond ZONE_DMA32.

For not fully explained reasons it broke mem=... on several setups.

Also minor cleanup.

Cc: axboe@suse.de
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/mm/init.c

@@ -262,19 +262,11 @@ static void __init find_early_table_space(unsigned long end)
 	tables = round_up(puds * sizeof(pud_t), PAGE_SIZE) +
 		 round_up(pmds * sizeof(pmd_t), PAGE_SIZE);
 
-	/* Put page tables beyond the DMA zones if possible.
-	   RED-PEN might be better to spread them out more over
-	   memory to avoid hotspots */
-	if (end > MAX_DMA32_PFN<<PAGE_SHIFT)
-		start = MAX_DMA32_PFN << PAGE_SHIFT;
-	else if (end > MAX_DMA_PFN << PAGE_SHIFT)
-		start = MAX_DMA_PFN << PAGE_SHIFT;
-	else
+ 	/* RED-PEN putting page tables only on node 0 could
+ 	   cause a hotspot and fill up ZONE_DMA. The page tables
+ 	   need roughly 0.5KB per GB. */
  	start = 0x8000;
-
  	table_start = find_e820_area(start, end, tables);
-	if (table_start == -1)
-		table_start = find_e820_area(0x8000, end, tables);
 	if (table_start == -1UL)
 		panic("Cannot find space for the kernel page tables");