[PATCH] Fix kunmap_atomic's use of kpte_clear_flush()

kunmap_atomic() will call kpte_clear_flush with vaddr/ptep arguments which
don't correspond if the vaddr is just a normal lowmem address (ie, not in
the KMAP area).  This patch makes sure that the pte is only cleared if kmap
area was actually used for the mapping.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 10 deletions

diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c
index 178bbfe6cbac..e0fa6cb655a8 100644
--- a/arch/i386/mm/highmem.c
+++ b/arch/i386/mm/highmem.c
@@ -50,22 +50,20 @@ void kunmap_atomic(void *kvaddr, enum km_type type)
         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 
-#ifdef CONFIG_DEBUG_HIGHMEM
-        if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
-                pagefault_enable();
-                return;
-        }
-
-        if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
-                BUG();
-#endif
         /*
          * Force other mappings to Oops if they'll try to access this pte
          * without first remap it.  Keeping stale mappings around is a bad idea
          * also, in case the page changes cacheability attributes or becomes
          * a protected page in a hypervisor.
          */
-        kpte_clear_flush(kmap_pte-idx, vaddr);
+        if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
+                kpte_clear_flush(kmap_pte-idx, vaddr);
+        else {
+#ifdef CONFIG_DEBUG_HIGHMEM
+                BUG_ON(vaddr < PAGE_OFFSET);
+                BUG_ON(vaddr >= (unsigned long)high_memory);
+#endif
+        }
 
         pagefault_enable();
 }