Re: [rfc] [patch] mm: zone_reclaim fix for pseudo file systems

Andrew Morton
2007-07-31T01:06:42Z

On Mon, 30 Jul 2007 17:27:41 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:

> On Mon, 30 Jul 2007, Andrew Morton wrote:
>
> > The problem is that __zone_reclaim() doesn't use all_unreclaimable at all.
> > You'll note that all the other callers of shrink_zone() do take avoiding
> > action if the zone is in all_unreclaimable state, but __zone_reclaim() forgot
> > to.
>
> zone reclaim only runs if there are unmapped file backed pages that can be
> reclaimed. If the pages are all unreclaimable then they are all mapped and
> global reclaim begins to run. The problem is with global reclaim as far as
> I know.

I don't understand how you conclude that.

- Kiran saw CPU meltdown when "one of the processes got into zone reclaim".

- all_unreclaimable is there specifically to prevent CPU meltdown

- zone_reclaim doesn't utilise all_unreclaimable.

so..