Date: Mon, 18 Apr 2005 22:07:12 +0200
From: Bernhard Fischer <blist@aon.at>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Timur Tabi <timur.tabi@ammasso.com>, linux-kernel@vger.kernel.org,
       openib-general@openib.org
Subject: Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation
Message-ID: <20050418200711.GI15688@aon.at>
References: <200544159.Ahk9l0puXy39U6u6@topspin.com> <20050411142213.GC26127@kalmia.hozed.org> <52mzs51g5g.fsf@topspin.com> <4263DBBF.9040801@ammasso.com> <1113840973.6274.84.camel@laptopd505.fenrus.org> <4263DF70.2060702@ammasso.com> <1113853240.6274.99.camel@laptopd505.fenrus.org>
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On Mon, Apr 18, 2005 at 09:40:40PM +0200, Arjan van de Ven wrote:
>On Mon, 2005-04-18 at 11:25 -0500, Timur Tabi wrote:
>> Arjan van de Ven wrote:
>> 
>> > this is a myth; linux is free to move the page about in physical memory
>> > even if it's mlock()ed!!
darn, yes, this is true.
I know people who introduced
#define VM_RESERVED     0x00080000      /* Don't unmap it from swap_out
*/
to vm_flags just because of this. I'll just hold my breath and won't
delve further.
>> 
>> Then Linux has a very odd definition of the word "locked".
>> 
>> > And even then, the user can munlock the memory from another thread etc
>> > etc. Not a good idea.
>> 
>> Well, that's okay, because then the app is doing something stupid, so we don't worry about 
>> that.
>
>you should since that physical page can be reused, say by a root
>process, and you'd be majorly screwed
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