linux-kernel - Re: [RFC V2] mm:add zero_page _mapcount when mapped into user space

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Date:	Tue, 2 Dec 2014 13:30:14 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	"Wang, Yalin" <Yalin.Wang@...ymobile.com>
Cc:	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'linux-mm@...ck.org'" <linux-mm@...ck.org>,
	"'linux-arm-kernel@...ts.infradead.org'" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC V2] mm:add zero_page _mapcount when mapped into user space

On Tue, Dec 02, 2014 at 05:27:36PM +0800, Wang, Yalin wrote:
> This patch add/dec zero_page's _mapcount to make sure
> the mapcount is correct for zero_page,
> so that when read from /proc/kpagecount, zero_page's
> mapcount is also correct, userspace process like procrank can
> calculate PSS correctly.

I don't have specific code path to point to, but I would expect zero page
with non-zero mapcount would cause a problem with rmap.

How do you test the change?

-- 
 Kirill A. Shutemov
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