Re: ptrace() and kernel tasks

Zack Weinberg (zack@rabi.columbia.edu)
Tue, 11 May 1999 17:42:51 -0400


On Tue, 11 May 1999 20:51:26 +0100, David Woodhouse wrote:
>
>zack@rabi.columbia.edu said:
>> IIRC your problem had to do with sysrq killall - maybe that's
>> different? in particular, sysrq sync is handled by kflushd, if it's
>> dead it won't do anything.
>
>SysRq "killall" doesn't hurt, but SysRq "killall even init" does.
>Also, if I boot with init=/bin/bash and then accidentally close the first
>bash, the system dies. I don't think it's because kflushd is getting killed.

I just did some experiments. `killall even init' does indeed render
my machine dead to all inputs. However, if I boot with
init=/bin/bash, open a shell on tty2, instruct the first bash to sleep
a few seconds and then exit, and switch to tty2, then... all normal
keyboard input is blackholed once process 1 exits, but sysrq continues
to work. sysrq-T shows a zombie init; the I/O daemons are fine;
sysrq-S syncs the disks and sysrq-B reboots.

I'm not in a position to check whether networking and serial I/O work
under these conditions. On its face, this looks to me like a bug in
the console driver. Incidentally, both forms of sysrq killall avoid
kernel threads, so that isn't relevant.

When was it your problem started?

zw

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/