linux-kernel - Re: [PATCH 5/5] extend KSM refcounts to the anon

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: <20100527143134.GA9505@barrios-desktop>
Date:	Thu, 27 May 2010 23:31:34 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Mel Gorman <mel@....ul.ie>,
	Andrea Arcangeli <aarcange@...hat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>
Subject: Re: [PATCH 5/5] extend KSM refcounts to the anon_vma root

On Wed, May 26, 2010 at 03:41:24PM -0400, Rik van Riel wrote:
> Subject: extend KSM refcounts to the anon_vma root
> 
> KSM reference counts can cause an anon_vma to exist after the processe
> it belongs to have already exited.  Because the anon_vma lock now lives
> in the root anon_vma, we need to ensure that the root anon_vma stays
> around until after all the "child" anon_vmas have been freed.
> 
> The obvious way to do this is to have a "child" anon_vma take a
> reference to the root in anon_vma_fork.  When the anon_vma is freed
> at munmap or process exit, we drop the refcount in anon_vma_unlink
> and possibly free the root anon_vma.
> 
> The KSM anon_vma reference count function also needs to be modified
> to deal with the possibility of freeing 2 levels of anon_vma.  The
> easiest way to do this is to break out the KSM magic and make it
> generic.
> 
> When compiling without CONFIG_KSM, this code is compiled out.
> 
> Signed-off-by: Rik van Riel <riel@...hat.com>
Reviewed-by: Minchan Kim <minchan.kim@...il.com>

Now I understand this patch. 
Thanks, Rik. 
-- 
Kind regards,
Minchan Kim
--
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/