From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757438Ab0E0OcP (ORCPT ); Thu, 27 May 2010 10:32:15 -0400 Received: from mail-pw0-f46.google.com ([209.85.160.46]:55023 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754518Ab0E0OcM (ORCPT ); Thu, 27 May 2010 10:32:12 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=m/yj5qG6Xb/ljqharKfQlqoY1gGrBrSzNeFcleDSPGbCIHNCfZAJRtsaATGK/2WAqA wgqLFMrgFqz0cAZzYI6S9q0GQU3yHnryMwNjobtMihbLpdsU7E+QclBUPQYS81r8e/TJ xCascRzzm59Gvdfkj51ne8BoJv/mxC47JUyM4= Date: Thu, 27 May 2010 23:31:34 +0900 From: Minchan Kim To: Rik van Riel Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mel Gorman , Andrea Arcangeli , KAMEZAWA Hiroyuki , Lee Schermerhorn Subject: Re: [PATCH 5/5] extend KSM refcounts to the anon_vma root Message-ID: <20100527143134.GA9505@barrios-desktop> References: <20100526153819.6e5cec0d@annuminas.surriel.com> <20100526154124.04607d04@annuminas.surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100526154124.04607d04@annuminas.surriel.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Reviewed-by: Minchan Kim Now I understand this patch. Thanks, Rik. -- Kind regards, Minchan Kim