Index: 2006-06-29/linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c
===================================================================
--- 2006-06-29.orig/linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c	2006-02-01 18:28:39.000000000 +0100
+++ 2006-06-29/linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c	2006-06-29 15:27:26.000000000 +0200
@@ -42,7 +42,7 @@ static void *__kmap_atomic(struct page *
 	if (!pte_none(*(kmap_pte-idx)))
 		BUG();
 #endif
-	set_pte_at_sync(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
+	set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
 
 	return (void*) vaddr;
 }
@@ -60,26 +60,27 @@ void *kmap_atomic_pte(struct page *page,
 
 void kunmap_atomic(void *kvaddr, enum km_type type)
 {
-#ifdef CONFIG_DEBUG_HIGHMEM
 	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 	enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 
-	if (vaddr < FIXADDR_START) { // FIXME
+	if (vaddr < (unsigned long)high_memory) {
 		dec_preempt_count();
 		preempt_check_resched();
 		return;
 	}
 
+#ifdef CONFIG_DEBUG_HIGHMEM
 	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
+	 * Also, let go of references Xen keeps for each mapping
+	 * a given page has.
 	 */
-	pte_clear(&init_mm, vaddr, kmap_pte-idx);
-	__flush_tlb_one(vaddr);
-#endif
+	set_pte_at_sync(&init_mm, vaddr, kmap_pte-idx, __pte_ma(0));
 
 	dec_preempt_count();
 	preempt_check_resched();