diff -ur /md0/kernels/2.4/v2.4.8-ac3/mm/memory.c vm-2.4.8-ac3/mm/memory.c
--- /md0/kernels/2.4/v2.4.8-ac3/mm/memory.c	Mon Aug 13 15:12:54 2001
+++ vm-2.4.8-ac3/mm/memory.c	Mon Aug 13 15:21:00 2001
@@ -452,7 +452,7 @@
 	if (err)
 		return err;
 
-	down_write(&mm->mmap_sem);
+	down_read(&mm->mmap_sem);
 
 	err = -EFAULT;
 	iobuf->locked = 0;
@@ -510,12 +510,12 @@
 		ptr += PAGE_SIZE;
 	}
 
-	up_write(&mm->mmap_sem);
+	up_read(&mm->mmap_sem);
 	dprintk ("map_user_kiobuf: end OK\n");
 	return 0;
 
  out_unlock:
-	up_write(&mm->mmap_sem);
+	up_read(&mm->mmap_sem);
 	unmap_kiobuf(iobuf);
 	dprintk ("map_user_kiobuf: end %d\n", err);
 	return err;