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Subject: Re: mlock'ed pages are paging out to shared mapped files?
From: Peter Zijlstra <peterz@infradead.org>
To: Bob Walters <bob.s.walters@gmail.com>
Cc: linux-kernel@vger.kernel.org
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References: <03A305FE-2E9E-42B0-A06C-564E03295B2A@gmail.com>
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Date: Fri, 26 Nov 2010 17:36:21 +0100
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On Fri, 2010-11-26 at 11:25 -0500, Bob Walters wrote:
> 
> Please CC directly, I'm not subscribed.
> 
> I'm writing to determine if observed mlock behavior is a bug or the
> intended implementation.   The kernel seems to be paging out
> modifications made to locked pages of a shared (MAP_SHARED) memory
> mapped regular file, on Linux 2.6.35.6-48 (Fedora 14 distro, x86_64).
> Man pages implies that this might be a bug.   I have a repeatable
> process involving the following test: 

That's not paged-out, its a shared mapping (ie a mapped file), you dirty
the pages, we clean them by writing them out to disk.

That is the expected behaviour, if the man-page implies anything else
its bonkers.