Re: the new VM

Andrea Arcangeli
2000-09-25T15:01:13Z

On Mon, Sep 25, 2000 at 04:43:44PM +0200, Ingo Molnar wrote:
> i talked about GFP_KERNEL, not GFP_USER. Even in the case of GFP_USER i

My bad, you're right I was talking about GFP_USER indeed.

But even GFP_KERNEL allocations like the init of a module or any other thing
that is static sized during production just checking the retval looks be ok.

> believe the right place to oom is via a signal, not in the gfp() case.

Signal can be trapped and ignored by malicious task. We had that security
problem until 2.2.14 IIRC.

> (because oom situation in the gfp() case is a completely random and
> statistical event, which might have no connection at all to the behavior
> of that given process.)

I agree we should have more information about the behaviour of the system
and I think a per-task page fault rate should work in practice.

But my question isn't what you do when you're OOM, but is _how_ do you
notice that you're OOM?

In the GFP_USER case simply checking when GFP fails looks right to me.

Andrea