--- linux-2.6.13/include/asm-i386/processor.h.orig	2005-09-01 11:19:22.000000000 +0800
+++ linux-2.6.13/include/asm-i386/processor.h	2005-09-01 11:26:04.000000000 +0800
@@ -538,11 +538,13 @@
        unsigned long *__ptr = (unsigned long *)(info);                 \
        (unsigned long)(&__ptr[THREAD_SIZE_LONGS]);                     \
 })
-
+/*
+ * subtract 8 here, to skip dummy offset, see copy_thread() for detailed comment.
+ */
 #define task_pt_regs(task)                                             \
 ({                                                                     \
        struct pt_regs *__regs__;                                       \
-       __regs__ = (struct pt_regs *)KSTK_TOP((task)->thread_info);     \
+       __regs__ = (struct pt_regs *)(KSTK_TOP((task)->thread_info)-8); \
        __regs__ - 1;                                                   \
 })