linux-kernel - Re: [PATCH 2/2] mm,migration: Avoid race between shift_arg_pages() and rmap_walk() during migration by not migrating temporary stacks

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: <alpine.DEB.2.00.1005101239400.13652@router.home>
Date:	Mon, 10 May 2010 12:41:07 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Mel Gorman <mel@....ul.ie>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Minchan Kim <minchan.kim@...il.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH 2/2] mm,migration: Avoid race between shift_arg_pages()
 and rmap_walk() during migration by not migrating temporary stacks

On Tue, 4 May 2010, Mel Gorman wrote:

> On Sat, May 01, 2010 at 08:56:18PM -0500, Christoph Lameter wrote:
> > On Thu, 29 Apr 2010, Mel Gorman wrote:
> >
> > > There is a race between shift_arg_pages and migration that triggers this bug.
> > > A temporary stack is setup during exec and later moved. If migration moves
> > > a page in the temporary stack and the VMA is then removed before migration
> > > completes, the migration PTE may not be found leading to a BUG when the
> > > stack is faulted.
> >
> > A simpler solution would be to not allow migration of the temporary stack?
> >
>
> The patch's intention is to not migrate pages within the temporary
> stack. What are you suggesting that is different?

A simple way to disallow migration of pages is to increment the refcount
of a 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/