Re: [PATCH] VM fix for 2.4.0-test9 & OOM handler

[Rik van Riel <riel@conectiva.com.br>]

On Tue, 10 Oct 2000, Philipp Rumpf wrote:
> On Tue, Oct 10, 2000 at 12:06:07PM -0300, Rik van Riel wrote:
> > On Tue, 10 Oct 2000, Philipp Rumpf wrote:
> > > > > The algorithm you posted on the list in this thread will kill
> > > > > init if on 4Mbyte machine without swap init is large 3 Mbytes
> > > > > and you execute a task that grows over 1M.
> > > > 
> > > > This sounds suspiciously like the description of a DEAD system ;)
> > > 
> > > But wouldn't a watchdog daemon which doesn't allocate any memory
> > > still get run ?
> > 
> > Indeed, it would. It would also /prevent/ the system
> > from automatically rebooting itself into a usable state ;)
> 
> So it's not dead in the "oh, it'll be back in 30 seconds" sense.  
> So our behaviour is broken (more so than random process
> killing).

*nod*

Not killing init when we "should" definately prevents
embedded systems from auto-rebooting when they should
do so.

(OTOH, I don't think embedded systems will run into
this OOM issue too much)

> > > You care about getting an automatic reboot.  So you need to be sure the
> > > watchdog daemon gets killed first or you panic() after some time.
> > 
> > echo 30 > /proc/sys/kernel/panic
> 
> that's what I said.  we need to be sure to _get_ a panic() though.

I believe the kernel automatically panic()s when init
dies ... from kernel/exit.c::do_exit()

        if (tsk->pid == 1)
                panic("Attempted to kill init!");

[which will make our system auto-reboot and be back on its feet
in a healty state again soon]

regards,

Rik
--
"What you're running that piece of shit Gnome?!?!"
       -- Miguel de Icaza, UKUUG 2000

http://www.conectiva.com/		http://www.surriel.com/

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