[PATCH] x86_64: Fix off by one in IOMMU check

Fix off by one when checking if the machine has enougn memory to need IOMMU
This caused the IOMMUs to be needlessly enabled for mem=4G

Based on a patch from Jon Mason

Signed-off-by: jdmason@us.ibm.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 1faae5fc1c01..5337ca0ea7b9 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -424,7 +424,7 @@ void __init mem_init(void)
 
 #ifdef CONFIG_SWIOTLB
         if (!iommu_aperture &&
-            (end_pfn >= 0xffffffff>>PAGE_SHIFT || force_iommu))
+            ((end_pfn-1) >= 0xffffffff>>PAGE_SHIFT || force_iommu))
                swiotlb = 1;
         if (swiotlb)
                 swiotlb_init();