linux-kernel - Re: [PATCH 3/3] mm,migration: Remove straggling migration PTEs when page tables are being moved after the VMA has already moved

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: <20100428010920.GK510@random.random>
Date:	Wed, 28 Apr 2010 03:09:20 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Mel Gorman <mel@....ul.ie>, Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Christoph Lameter <cl@...ux.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 3/3] mm,migration: Remove straggling migration PTEs
 when page tables are being moved after the VMA has already moved

On Wed, Apr 28, 2010 at 03:05:43AM +0200, Andrea Arcangeli wrote:
> 1) adjusting page->index atomically with the pte updates inside pt
>    lock (while it moves from one pte to another)

actually no need of this at all! of course the dst vma will have
vma->vm_pgoff adjusted instead... never mind. So I don't see a problem
there.

I think this is very special of how exec.c abuses move_page_tables by
passing vma as src and dst, when it obviously cannot be indexed in two
anon-vmas because there's a single vma and a single vma->anon_vma, and
src and dst obviously cannot have two different vm_pgoff again because
there's a single vma and there can't be two different vma->vm_pgoff.

So I'm very hopeful do_mremap is already fully safe...
--
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/