--- linux-2.6.21.2/arch/um/kernel/trap.c.orig	2007-05-24 02:22:42.000000000 -0700
+++ linux-2.6.21.2/arch/um/kernel/trap.c	2007-05-24 02:23:45.000000000 -0700
@@ -51,6 +51,9 @@
 	 * fail. */
 	if (in_atomic())
 		goto out_nosemaphore;
+	/* If we have no user-space just fail */
+	if (!mm)
+		goto out_nosemaphore;
 
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);