Re: KPATCH] Reserve VM for root (was: Re: Looking for better VM)

Pavel Machek
2000-11-18T20:49:06Z

Hi!

> > >main() { while(1) if (fork()) malloc(1); }
> > >With the patch below I could ssh to the host and killall the offending
> > >processes. To enable reserving VM space for root do
> > what about main() { while(1) system("ftp localhost &"); }
> > This. or so,ething similar should allow you to kill your machine
> > even with your patch from normal user account
>
> This or something similar didn't kill the box [I've tried all local
> DoS from Packetstorm that I could find]. Please send a working

Sorry, I did not have working example, just feeling that something
like that should be possible.

> Note, I'm not discussing "local user can kill the box without limits",
> I say Linux "deadlocks" [it starts its own autonom life and usually
> your only chance is to hit the reset button] when there is continuous
> VM pressure by user applications. If you think fork() kills the box

That's clear bug, right? It should not deadlock, it should go to
OOM-killer and kill someone.

> BTW, I have a new version of the patch with that Linux behaves much
> better from root's point of view when the memory is more significantly
> overcommited. I'll post it if I have time [and there is interest].

There is interest. Yesterday atrey died due userland process eating
all memory.
Pavel
PS: atrey is machine that gets my mail, so it is kind of important to
me.
--
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org