linux-kernel - Re: [RFC] Track mlock()ed pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.64.0701261021200.7848@schroedinger.engr.sgi.com>
Date:	Fri, 26 Jan 2007 10:23:44 -0800 (PST)
From:	Christoph Lameter <clameter@....com>
To:	Andrew Morton <akpm@...l.org>
cc:	Nick Piggin <nickpiggin@...oo.com.au>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] Track mlock()ed pages

On Fri, 26 Jan 2007, Andrew Morton wrote:

> > Large amounts of mlocked pages may be a problem for 
> > 
> > 1. Reclaim behavior.
> > 
> > 2. Defragmentation
> > 
> 
> We know that.  What has that to do with this patch?

Knowing how much mlocked pages are where is necessary to solve these 
issues.

> > > You could perhaps go for a walk across all the other vmas which presently
> > > map this page.  If any of them have VM_LOCKED, don't increment the counter.
> > > Similar on removal: only decrement the counter when the final mlocked VMA
> > > is dropping the pte.
> > 
> > For that we would need an additional refcount for vmlocked maps in the 
> > page struct.
> 
> No you don't.  The refcount is already there.  It is "the sum of the VM_LOCKED
> VMAs which map this page".
> 
> It might be impractical or expensive to calculate it, but it's there.

Correct. Its so expensive that it cannot be used to build vm stats for 
mlocked pages. F.e. Determination of the final mlocked VMA dropping the 
page would require a scan over all vmas mapping the page.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/