diff -Naurp linux-2.4.20/include/linux/sched.h linux-2.4.20-ptrace/include/linux/sched.h
--- linux-2.4.20/include/linux/sched.h	2003-03-20 14:35:49.000000000 +0100
+++ linux-2.4.20-ptrace/include/linux/sched.h	2003-04-07 18:20:45.000000000 +0200
@@ -478,7 +479,7 @@ struct task_struct {
 #define PT_TRACESYSGOOD	0x00000008
 #define PT_PTRACE_CAP	0x00000010	/* ptracer can follow suid-exec */
 
-#define is_dumpable(tsk)	((tsk)->task_dumpable && (tsk)->mm->dumpable)
+#define is_dumpable(tsk)	((tsk)->task_dumpable && (tsk)->mm && (tsk)->mm->dumpable)
 
 /*
  * Limit the stack by to some sane default: root can always