linux-kernel - Re: Fwd: Control page reclaim granularity

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Message-ID: <20120313082818.GA5421@gmail.com>
Date:	Tue, 13 Mar 2012 16:28:18 +0800
From:	Zheng Liu <gnehzuil.liu@...il.com>
To:	Kautuk Consul <consul.kautuk@...il.com>
Cc:	minchan@...nel.org, riel@...hat.com,
	kosaki.motohiro@...fujitsu.com, Zheng Liu <wenqing.lz@...bao.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: Fwd: Control page reclaim granularity

On Tue, Mar 13, 2012 at 01:38:56PM +0530, Kautuk Consul wrote:
> >
> > I agree, but that's not my point.
> >
> > All I'm saying is that we probably don't want to give normal
> > unprivileged usermode apps
> > the capability to set the mapping to AS_UNEVICTABLE as anyone can then
> > write an application
> > that hogs memory without allowing the kernel to free it through memory reclaim.

Yes, I think so.  But it seems that there has some codes that are
possible to be abused.  For example, as I said previously, applications
can mmap a normal data file with PROT_EXEC flag.  Then this file gets a
high priority to keep in memory (commit: 8cab4754).  So my point is that
we cannot control applications how to use these mechanisms.  We just
provide them and let applications to choose how to use them.
:-)

Regards,
Zheng

> 
> Sorry, I mean :
> "... that hogs kernel unmapped page-cache memory without allowing the
> kernel to free it through memory reclaim."
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