linux-kernel - Re: [PATCH 2/4] Add replace_page(), change the mapping of pte from one page into another

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]

Date:	Tue, 11 Nov 2008 15:26:57 -0600 (CST)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	Andrea Arcangeli <aarcange@...hat.com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Izik Eidus <ieidus@...hat.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, kvm@...r.kernel.org, chrisw@...hat.com,
	avi@...hat.com, izike@...ranet.com
Subject: Re: [PATCH 2/4] Add replace_page(), change the mapping of pte from
 one page into another

On Tue, 11 Nov 2008, Andrea Arcangeli wrote:

> btw, page_migration likely is buggy w.r.t. o_direct too (and now
> unfixable with gup_fast until the 2.4 brlock is added around it or
> similar) if it does the same thing but without any page_mapcount vs
> page_count check.

Details please?

> page_migration does too much for us, so us calling into migrate.c may
> not be ideal. It has to convert a fresh page to a VM page. In KSM we
> don't convert the newpage to be a VM page, we just replace the anon
> page with another page. The new page in the KSM case is not a page
> known by the VM, not in the lru etc...

A VM page as opposed to pages not in the VM? ???

page migration requires the page to be on the LRU. That could be changed
if you have a different means of isolating a page from its page tables.

> The way to go could be to change the page_migration to use
> replace_page (or __replace_page if called in some shared inner-lock
> context) after preparing the newpage to be a regular VM page. If we
> can do that, migrate.c will get the o_direct race fixed too for free.

Define a regular VM page? A page on the LRU?

--
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/