Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes

[Minchan Kim]

On Mon, Mar 06, 2017 at 11:24:10AM -0500, Johannes Weiner wrote:
> On Mon, Mar 06, 2017 at 10:37:40AM +0900, Minchan Kim wrote:
> > On Fri, Mar 03, 2017 at 08:59:54AM +0100, Michal Hocko wrote:
> > > On Fri 03-03-17 10:26:09, Minchan Kim wrote:
> > > > On Tue, Feb 28, 2017 at 04:39:59PM -0500, Johannes Weiner wrote:
> > > > > @@ -3316,6 +3325,9 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
> > > > >  			sc.priority--;
> > > > >  	} while (sc.priority >= 1);
> > > > >  
> > > > > +	if (!sc.nr_reclaimed)
> > > > > +		pgdat->kswapd_failures++;
> > > > 
> > > > sc.nr_reclaimed is reset to zero in above big loop's beginning so most of time,
> > > > it pgdat->kswapd_failures is increased.
> 
> That wasn't intentional; I didn't see the sc.nr_reclaimed reset.
> 
> ---
> 
> From e126db716926ff353b35f3a6205bd5853e01877b Mon Sep 17 00:00:00 2001
> From: Johannes Weiner <hannes@xxxxxxxxxxx>
> Date: Mon, 6 Mar 2017 10:53:59 -0500
> Subject: [PATCH] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes fix
> 
> Check kswapd failure against the cumulative nr_reclaimed count, not
> against the count from the lowest priority iteration.
> 
> Suggested-by: Minchan Kim <minchan@xxxxxxxxxx>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>