1 files changed, 2 insertions, 3 deletions

diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index e66311200cbd..b574b295a2f9 100644
--- a/arch/x86/kernel/amd_gart_64.c
+++ b/arch/x86/kernel/amd_gart_64.c
@@ -768,10 +768,9 @@ int __init gart_iommu_init(void)
         aper_base       = info.aper_base;
         end_pfn         = (aper_base>>PAGE_SHIFT) + (aper_size>>PAGE_SHIFT);
 
-        if (end_pfn > max_low_pfn_mapped) {
-                start_pfn = (aper_base>>PAGE_SHIFT);
+        start_pfn = PFN_DOWN(aper_base);
+        if (!pfn_range_is_mapped(start_pfn, end_pfn))
                 init_memory_mapping(start_pfn<<PAGE_SHIFT, end_pfn<<PAGE_SHIFT);
-        }
 
         pr_info("PCI-DMA: using GART IOMMU.\n");
         iommu_size = check_iommu_size(info.aper_base, aper_size);