linux-kernel - Re: [PATCH 4/5] always lock the root (oldest) 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]

Date:	Thu, 27 May 2010 22:55:07 +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 4/5] always lock the root (oldest) anon_vma

On Wed, May 26, 2010 at 03:40:44PM -0400, Rik van Riel wrote:
> Subject: always lock the root (oldest) anon_vma
> 
> Always (and only) lock the root (oldest) anon_vma whenever we do something in an
> anon_vma.  The recently introduced anon_vma scalability is due to the rmap code
> scanning only the VMAs that need to be scanned.  Many common operations still
> took the anon_vma lock on the root anon_vma, so always taking that lock is not
> expected to introduce any scalability issues.
> 
> However, always taking the same lock does mean we only need to take one lock,
> which means rmap_walk on pages from any anon_vma in the vma is excluded from
> occurring during an munmap, expand_stack or other operation that needs to
> exclude rmap_walk and similar functions.
> 
> Also add the proper locking to vma_adjust.
> 
> Signed-off-by: Rik van Riel <riel@...hat.com>
Reviewed-by: Minchan Kim <minchan.kim@...il.com>

Nitpick:

It would be better to modify comment about head of anon_vma in rmap.h, too.
/*  
 * NOTE: the LSB of the head.next is set by
                   ->   root->hext.next 
-- 
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/