linux-kernel - Re: Kernel falls apart under light memory pressure (i.e. linking vmlinux)

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Message-ID: <20110516085117.GA4743@csn.ul.ie>
Date:	Mon, 16 May 2011 09:51:17 +0100
From:	Mel Gorman <mel@....ul.ie>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	Andrew Lutomirski <luto@....edu>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: Kernel falls apart under light memory pressure (i.e. linking
 vmlinux)

On Mon, May 16, 2011 at 07:58:01AM +0900, Minchan Kim wrote:
> On Mon, May 16, 2011 at 12:59 AM, Andrew Lutomirski <luto@....edu> wrote:
> > I have no clue, but this patch (from Minchan, whitespace-damaged) seems to help:
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index f6b435c..4d24828 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -2251,6 +2251,10 @@ static bool sleeping_prematurely(pg_data_t
> > *pgdat, int order, long remaining,
> >       unsigned long balanced = 0;
> >       bool all_zones_ok = true;
> >
> > +       /* If kswapd has been running too long, just sleep */
> > +       if (need_resched())
> > +               return false;
> > +
> >       /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
> >       if (remaining)
> >               return true;
> > @@ -2286,7 +2290,7 @@ static bool sleeping_prematurely(pg_data_t
> > *pgdat, int order, long remaining,
> >        * must be balanced
> >        */
> >       if (order)
> > -               return pgdat_balanced(pgdat, balanced, classzone_idx);
> > +               return !pgdat_balanced(pgdat, balanced, classzone_idx);
> >       else
> >               return !all_zones_ok;
> >  }
> >
> > I haven't tested it very thoroughly, but it's survived much longer
> > than an unpatched kernel probably would have under moderate use.
> >
> > I have no idea what the patch does :)
> 
> The reason I sent this is that I think your problem is similar to
> recent Jame's one.
> https://lkml.org/lkml/2011/4/27/361
> 
> What the patch does is [1] fix of "wrong pgdat_balanced return value"
> bug and [2] fix of "infinite kswapd bug of non-preemption kernel" on
> high-order page.
> 

If it turns out the patch works (which is patches 1 and 4 from the
series related to James) for more than one tester, I'll push it
separately and drop the SLUB changes.

-- 
Mel Gorman
SUSE Labs
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