Re: [RFC 0/3] Recursive reclaim (on __PF_MEMALLOC)

Nick Piggin
2007-09-05T12:19:48Z

On Wed, Sep 05, 2007 at 05:14:06AM -0700, Christoph Lameter wrote:
> On Wed, 5 Sep 2007, Nick Piggin wrote:
>
> > However I really have an aversion to the near enough is good enough way of
> > thinking. Especially when it comes to fundamental deadlocks in the VM. I
> > don't know whether Peter's patch is completely clean yet, but fixing the
> > fundamentally broken code has my full support.
>
> Uhh. There are already numerous other issues why the VM is failing that is
> independent of Peter's approach.

I don't know what your point is? We either ignore it, or try to fix things
one at a time.

> > I hate it that there are theoretical bugs still left even if they would
> > be hit less frequently than hardware failure. And that people are really
> > happy to put even more of these things in :(
>
> Theoretical bugs? Depends on one's creativity to come up with them I
> guess. So far we do not even get around to address the known issues and
> this multi subsystem patch has the potential of creating more.

I can't direct people as to what bugs to work on.

> > Anyway, as you know I like your patch and if that gives Peter a little
> > more breathing space then it's a good thing. But I really hope he doesn't
> > give up on it, and it should be merged one day.
>
> Using the VM to throttle networking is a pretty bad thing because it
> assumes single critical user of memory. There are other consumers of
> memory and if you have a load that depends on other things than networking
> then you should not kill the other things that want memory.

Implementation issues aside, the problem is there and I would like to
see it fixed regardless if some/most/or all users in practice don't
hit it.