Re: Total system lockup with Alt-SysRQ-L

[Russell King <rmk@arm.linux.org.uk>]

On Mon, Dec 24, 2001 at 02:34:20AM +0000, Alan Cox wrote:
> > When pid1 exits (maybe due to a kill signal), we lockup hard in (iirc)
> > exit_notify.  I don't remember the details I'm afraid.
> 
> pid1 ends up trying to kill pid1 and it goes deeply down the toilet from
> that point onwards. The Unix traditional world reboots when pid 1 dies.

The problem was definitely in the exit_notify code, where it manipulated
the task links indefinitely.  (I think it was cptr never becomes null,
so the loop never terminates).

However, if we're saying that "pid1 must not die" then maybe we should get
rid of the 'killall' sysrq option since it serves no useful purpose, and
add a suitable panic in the do_exit path?

I'll generate a patch for that if there's interest.

--
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html