Date: Tue, 13 Feb 2007 14:57:09 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: andi@firstfloor.org, linux-kernel@vger.kernel.org,
       torvalds@linux-foundation.org, arjan@infradead.org, hch@infradead.org,
       akpm@zip.com.au, alan@lxorguk.ukuu.org.uk, drepper@redhat.com,
       zach.brown@oracle.com, johnpol@2ka.mipt.ru, davem@davemloft.net,
       bcrl@kvack.org, suparna@in.ibm.com, davidel@xmailserver.org,
       tglx@linutronix.de
Subject: Re: [patch 05/11] syslets: core code
Message-Id: <20070213145709.323a6505.akpm@linux-foundation.org>
In-Reply-To: <20070213222443.GH22104@elte.hu>
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	<p73bqjxhcnl.fsf@bingen.suse.de>
	<20070213222443.GH22104@elte.hu>
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> On Tue, 13 Feb 2007 23:24:43 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> > If it's only a few pages you don't need any resource accounting. If 
> > it's more then it's nasty to steal the users quota. I think plain 
> > gup() would be better.
> 
> get_user_pages() would have to be limited in some way - and i didnt want 
> to add yet another wacky limit thing - so i just used the already 
> existing mlock() infrastructure for this. If Oracle wants to set up a 10 
> MB ringbuffer, they can set the PAM resource limits to 11 MB and still 
> have enough stuff left. And i dont really expect GPG to start using 
> syslets - just yet ;-)
> 
> a single page is enough for 1024 completion pointers - that's more than 
> enough for most purposes - and the default mlock limit is 40K.

So if I have an application which instantiates a single mlocked page
for this purpose, I can only run ten of them at once, and any other
mlock-using process which I'm using starts to mysteriously fail.

It seems like a problem to me..
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