Re: [PATCH] mm: Check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE

[John Stultz <john.stultz@linaro.org>]

On Tue, 2011-04-26 at 18:49 +0900, KOSAKI Motohiro wrote:
> > On Thu, Apr 21, 2011 at 06:34:03PM -0700, John Stultz wrote:
> > > From: Arve Hjønnevåg <arve@android.com>
> > > 
> > > This fixes a problem where the first pageblock got marked MIGRATE_RESERVE even
> > > though it only had a few free pages. This in turn caused no contiguous memory
> > > to be reserved and frequent kswapd wakeups that emptied the caches to get more
> > > contiguous memory.
> > > 
> > > CC: Dave Hansen <dave@linux.vnet.ibm.com>
> > > CC: Mel Gorman <mgorman@suse.de>
> > > CC: Andrew Morton <akpm@linux-foundation.org>
> > > Signed-off-by: Arve Hjønnevåg <arve@android.com>
> > > Acked-by: Mel Gorman <mel@csn.ul.ie>
> > > 
> > > [This patch was submitted and acked a little over a year ago
> > > (see: http://lkml.org/lkml/2010/4/6/172 ), but never seemingly
> > > made it upstream. Resending for comments. -jstultz]
> > > 
> > > Signed-off-by: John Stultz <john.stultz@linaro.org>
> > 
> > Whoops, should have spotted it slipped through. FWIW, I'm still happy
> > with my Ack being stuck onto it.
> 
> Hehe, No.
> 
> You acked another patch at last year and John taked up old one. Sigh.
> Look,  correct one has pfn_valid_within(). 
> 	http://lkml.org/lkml/2010/4/6/172

Oh yikes! Many thanks for noticing that detail! Indeed, I started with
the patch in the Android tree, and didn't notice the difference in the
discussion I linked to. My apologies.

> And, Minchan suggested to add more explanation to the description. Then, I think
> following is desiable one.

Thanks so much again!
-john