linux-kernel - Re: a patch drop request in -mm

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Date:	Thu, 24 Sep 2009 09:40:34 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Mel Gorman <mel@....ul.ie>
Cc:	kosaki.motohiro@...fujitsu.com,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	Lee Schermerhorn <Lee.Schermerhorn@...com>
Subject: Re: a patch drop request in -mm

> On Tue, Sep 22, 2009 at 12:00:51AM +0900, KOSAKI Motohiro wrote:
> > Mel,
> > 
> > Today, my test found following patch makes false-positive warning.
> > because, truncate can free the pages
> > although the pages are mlock()ed.
> > 
> > So, I think following patch should be dropped.
> > .. or, do you think truncate should clear PG_mlock before free the page?
> 
> Is there a reason that truncate cannot clear PG_mlock before freeing the
> page?

CC to Lee.
IIRC, Lee tried it at first. but after some trouble, he decided change free_hot_cold_page().
but unfortunately, I don't recall the reason ;-)

Lee, Can you recall it?


> > Can I ask your patch intention?
> 
> Locked pages being freed to the page allocator were considered
> unexpected and a counter was in place to determine how often that
> situation occurred. However, I considered it unlikely that the counter
> would be noticed so the warning was put in place to catch what class of
> pages were getting freed locked inappropriately. I think a few anomolies
> have been cleared up since. Ultimately, it should have been safe to
> delete the check.

OK. it seems reasonable. so, I only hope no see linus tree output false-positive warnings.
Thus, I propse 

  - don't merge this patch to linus tree
  - but, no drop from -mm
    it be holded in mm until this issue fixed.
  - I'll working on fixing this issue.

I think this is enough fair.


Hannes, I'm sorry. I haven't review your patch. I'm too busy now. please gime me more
sevaral time.



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