linux-kernel - Re: [PATCH] Revert "mm: remove __GFP_NO

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Date:	Mon, 19 Nov 2012 20:43:43 -0500
From:	Valdis.Kletnieks@...edu
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Josh Boyer <jwboyer@...il.com>, Mel Gorman <mgorman@...e.de>,
	Zdenek Kabelac <zkabelac@...hat.com>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Jiri Slaby <jslaby@...e.cz>, Jiri Slaby <jirislaby@...il.com>,
	linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Robert Jennings <rcj@...ux.vnet.ibm.com>
Subject: Re: [PATCH] Revert "mm: remove __GFP_NO_KSWAPD"

On Fri, 16 Nov 2012 11:51:24 -0800, Andrew Morton said:
> On Fri, 16 Nov 2012 14:14:47 -0500
> Josh Boyer <jwboyer@...il.com> wrote:
>
> > > The temptation is to supply a patch that checks if kswapd was woken for
> > > THP and if so ignore pgdat->kswapd_max_order but it'll be a hack and not
> > > backed up by proper testing. As 3.7 is very close to release and this is
> > > not a bug we should release with, a safer path is to revert "mm: remove
> > > __GFP_NO_KSWAPD" for now and revisit it with the view to ironing out the
> > > balance_pgdat() logic in general.
> > >
> > > Signed-off-by: Mel Gorman <mgorman@...e.de>
> >
> > Does anyone know if this is queued to go into 3.7 somewhere?  I looked
> > a bit and can't find it in a tree.  We have a few reports of Fedora
> > rawhide users hitting this.
>
> Still thinking about it.  We're reverting quite a lot of material
> lately.
> mm-revert-mm-vmscan-scale-number-of-pages-reclaimed-by-reclaim-compaction-based-on-failures.patch
> and revert-mm-fix-up-zone-present-pages.patch are queued for 3.7.
>
> I'll toss this one in there as well, but I can't say I'm feeling
> terribly confident.  How is Valdis's machine nowadays?

I admit possibly having lost the plot.  With the two patches you mention stuck
on top of next-20121114, I'm seeing less kswapd issues but am still tripping
over them on occasion.  It seems to be related to uptime - I don't see any for
a few hours, but they become more frequent.  I was seeing quite a few of them
yesterday after I had a 30-hour uptime.

I'll stick Mel's "mm: remove __GFP_NO_KSWAPD" patch on this evening and let you
know what happens (might be a day or two before I have definitive results, as
usualally my laptop gets rebooted twice a day).


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