diff --git a/Documentation/ia64/aliasing-test.c b/Documentation/ia64/aliasing-test.c
index d485256ee1ce..773a814d4093 100644
--- a/Documentation/ia64/aliasing-test.c
+++ b/Documentation/ia64/aliasing-test.c
@@ -19,6 +19,7 @@
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <linux/pci.h>
 
 int sum;
 
@@ -34,13 +35,19 @@ int map_mem(char *path, off_t offset, size_t length, int touch)
 		return -1;
 	}
 
+	if (fnmatch("/proc/bus/pci/*", path, 0) == 0) {
+		rc = ioctl(fd, PCIIOC_MMAP_IS_MEM);
+		if (rc == -1)
+			perror("PCIIOC_MMAP_IS_MEM ioctl");
+	}
+
 	addr = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, offset);
 	if (addr == MAP_FAILED)
 		return 1;
 
 	if (touch) {
 		c = (int *) addr;
-		while (c < (int *) (offset + length))
+		while (c < (int *) (addr + length))
 			sum += *c++;
 	}
 
@@ -54,7 +61,7 @@ int map_mem(char *path, off_t offset, size_t length, int touch)
 	return 0;
 }
 
-int scan_sysfs(char *path, char *file, off_t offset, size_t length, int touch)
+int scan_tree(char *path, char *file, off_t offset, size_t length, int touch)
 {
 	struct dirent **namelist;
 	char *name, *path2;
@@ -93,7 +100,7 @@ int scan_sysfs(char *path, char *file, off_t offset, size_t length, int touch)
 		} else {
 			r = lstat(path2, &buf);
 			if (r == 0 && S_ISDIR(buf.st_mode)) {
-				rc = scan_sysfs(path2, file, offset, length, touch);
+				rc = scan_tree(path2, file, offset, length, touch);
 				if (rc < 0)
 					return rc;
 			}
@@ -238,10 +245,15 @@ int main()
 	else
 		fprintf(stderr, "FAIL: /dev/mem 0x0-0x100000 not accessible\n");
 
-	scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1);
-	scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0);
-	scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1);
-	scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0);
+	scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1);
+	scan_tree("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0);
+	scan_tree("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1);
+	scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0);
 
 	scan_rom("/sys/devices", "rom");
+
+	scan_tree("/proc/bus/pci", "??.?", 0, 0xA0000, 1);
+	scan_tree("/proc/bus/pci", "??.?", 0xA0000, 0x20000, 0);
+	scan_tree("/proc/bus/pci", "??.?", 0xC0000, 0x40000, 1);
+	scan_tree("/proc/bus/pci", "??.?", 0, 1024*1024, 0);
 }
diff --git a/Documentation/ia64/aliasing.txt b/Documentation/ia64/aliasing.txt
index 9a431a7d0f5d..aa3e953f0f7b 100644
--- a/Documentation/ia64/aliasing.txt
+++ b/Documentation/ia64/aliasing.txt
@@ -112,6 +112,18 @@ POTENTIAL ATTRIBUTE ALIASING CASES
 
 	The /dev/mem mmap constraints apply.
 
+    mmap of /proc/bus/pci/.../??.?
+
+    	This is an MMIO mmap of PCI functions, which additionally may or
+	may not be requested as using the WC attribute.
+
+	If WC is requested, and the region in kern_memmap is either WC
+	or UC, and the EFI memory map designates the region as WC, then
+	the WC mapping is allowed.
+
+	Otherwise, the user mapping must use the same attribute as the
+	kernel mapping.
+
     read/write of /dev/mem
 
 	This uses copy_from_user(), which implicitly uses a kernel
diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
index 73696b4a2eed..07d0e92742c8 100644
--- a/arch/ia64/pci/pci.c
+++ b/arch/ia64/pci/pci.c
@@ -591,6 +591,9 @@ int
 pci_mmap_page_range (struct pci_dev *dev, struct vm_area_struct *vma,
 		     enum pci_mmap_state mmap_state, int write_combine)
 {
+	unsigned long size = vma->vm_end - vma->vm_start;
+	pgprot_t prot;
+
 	/*
 	 * I/O space cannot be accessed via normal processor loads and
 	 * stores on this platform.
@@ -604,15 +607,24 @@ pci_mmap_page_range (struct pci_dev *dev, struct vm_area_struct *vma,
 		 */
 		return -EINVAL;
 
+	if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
+		return -EINVAL;
+
+	prot = phys_mem_access_prot(NULL, vma->vm_pgoff, size,
+				    vma->vm_page_prot);
+
 	/*
-	 * Leave vm_pgoff as-is, the PCI space address is the physical
-	 * address on this platform.
+	 * If the user requested WC, the kernel uses UC or WC for this region,
+	 * and the chipset supports WC, we can use WC. Otherwise, we have to
+	 * use the same attribute the kernel uses.
 	 */
-	if (write_combine && efi_range_is_wc(vma->vm_start,
-					     vma->vm_end - vma->vm_start))
+	if (write_combine &&
+	    ((pgprot_val(prot) & _PAGE_MA_MASK) == _PAGE_MA_UC ||
+	     (pgprot_val(prot) & _PAGE_MA_MASK) == _PAGE_MA_WC) &&
+	    efi_range_is_wc(vma->vm_start, vma->vm_end - vma->vm_start))
 		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 	else
-		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+		vma->vm_page_prot = prot;
 
 	if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 			     vma->vm_end - vma->vm_start, vma->vm_page_prot))