From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 95C00600385 for ; Thu, 27 May 2010 10:31:43 -0400 (EDT) Received: by pzk11 with SMTP id 11so32165pzk.28 for ; Thu, 27 May 2010 07:31:42 -0700 (PDT) Date: Thu, 27 May 2010 23:31:34 +0900 From: Minchan Kim 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> Sender: owner-linux-mm@kvack.org 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 List-ID: 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org