Attached is a simple patch to fix the return value from the 64-bit kernel when you call with a bad system call number with tracing enabled (for either ptrace or audit). What should happen is that the user process gets a -ENOSYS return call from the syscall; what actually happens (only in the 64-bit kernel) is that you get back the system call number. The 32-bit kernel does not suffer from this bug, and the pv-ops implementation in the upstream Linux kernel also does not have this bug. The attached patch makes the tracesys path look the same as it does in upstream Linux, and ensures that we return -ENOSYS on this path. Signed-off-by: Chris Lalancette