Re: kswapd in tight loop 2.6.9-rc3-bk-recent

[Nick Piggin]

Andrew Morton wrote:

> Nick Piggin <piggin@xxxxxxxxxxxxxxx> wrote:
>
> > > Chris Wright <chrisw@xxxxxxxx> wrote:
> > >
> > >>(whereas I could get the mainline code, and the
> > >> one-liner to spin right off).  
> > >>
> > >
> > >How?  (up to and including .config please).
> > >
> > >
> > >
> >
> > Ah, free_pages <= pages_high, ie. 0 <= 0, which is true;
> > commence spinning.
>
> Maybe.  It requires that the zonelists be screwy:
>
> Node 1 DMA free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB
> protections[]: 0 0 0
> Node 1 Normal free:25272kB min:1020kB low:2040kB high:3060kB active:624172kB inactive:282700kB present:1047936kB
> protections[]: 0 0 0
> Node 1 HighMem free:0kB min:128kB low:256kB high:384kB active:0kB inactive:0kB present:0kB
> protections[]: 0 0 0
> Node 0 DMA free:728kB min:12kB low:24kB high:36kB active:788kB inactive:7848kB present:16384kB
> protections[]: 0 0 0
> Node 0 Normal free:27200kB min:1004kB low:2008kB high:3012kB active:332792kB inactive:422744kB present:1032188kB
> protections[]: 0 0 0
> Node 0 HighMem free:0kB min:128kB low:256kB high:384kB active:0kB inactive:0kB present:0kB
> protections[]: 0 0 0
>
> See that DMA zone on node 1?  Wonder how it got like that.  It
> should not be inside pgdat->nrzones anyway.
Oh? Why not? I didn't think empty zones were filtered out? (perhaps
they should be).

> David, is your setup NUMA?  Can you show us a sysrq-M dump?

Yes. Incase he's alseep, I'll quote:

"I saw the same thing yesterday, also on an amd64 box though that
could be coincidence. The kswapd1 process was pegging the cpu at 99%
kswapd0 was idle. After a few minutes, the box became so unresponsive"

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