linux-kernel - Re: [RFC] Tracking mlocked pages and moving them off the LRU

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20070205163847.GI16722@waste.org>
Date:	Mon, 5 Feb 2007 10:38:47 -0600
From:	Matt Mackall <mpm@...enic.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Christoph Lameter <clameter@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Nick Piggin <nickpiggin@...oo.com.au>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [RFC] Tracking mlocked pages and moving them off the LRU

On Mon, Feb 05, 2007 at 09:39:34AM +0100, Arjan van de Ven wrote:
> On Sun, 2007-02-04 at 23:57 -0800, Christoph Lameter wrote:
> > Hmmm.. I have had no time to test this one yet but I think this should 
> > work. It uses the delayed method and a new page flag PageMlocked() with 
> > different semantics. Fix for page migration is also included.
> > 
> > Patch avoids to put new anonymous mlocked pages on the LRU. Maybe the same 
> > could be done for new pagecache pages?
> > 
> > I still need a solution for the problem of not having enough page flag 
> > bits on i386 NUMA.
> 
> I still don't get why you *really* need such a bit. 

There are three possibilities mentioned so far:

1) slow accounting - scan each attached VMA on each mmap/munmap
2) lazy accounting - the same as above, with the work all moved to the
LRU sweep
3) accounting with an extra page flag - still needs to scan VMAs on munmap

Christoph seems to prefer the third.

I wonder if we couldn't stick a rough counter in address_space to
fast-path the slow accounting - we'll typically only have 0 or 1 locks
active.

-- 
Mathematics is the supreme nostalgia of our time.
-
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/