From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 89C796B007D for ; Fri, 19 Feb 2010 16:58:44 -0500 (EST) Date: Fri, 19 Feb 2010 21:58:26 +0000 From: Mel Gorman Subject: Re: [PATCH 03/12] mm: Share the anon_vma ref counts between KSM and page migration Message-ID: <20100219215826.GF1445@csn.ul.ie> References: <1266516162-14154-1-git-send-email-mel@csn.ul.ie> <1266516162-14154-4-git-send-email-mel@csn.ul.ie> <4B7F05BA.4080903@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <4B7F05BA.4080903@redhat.com> Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, Feb 19, 2010 at 04:42:18PM -0500, Rik van Riel wrote: > On 02/18/2010 01:02 PM, Mel Gorman wrote: > >> struct anon_vma { >> spinlock_t lock; /* Serialize access to vma list */ >> -#ifdef CONFIG_KSM >> - atomic_t ksm_refcount; >> -#endif >> -#ifdef CONFIG_MIGRATION >> - atomic_t migrate_refcount; >> +#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) >> + >> + /* >> + * The refcount is taken by either KSM or page migration >> + * to take a reference to an anon_vma when there is no >> + * guarantee that the vma of page tables will exist for >> + * the duration of the operation. A caller that takes >> + * the reference is responsible for clearing up the >> + * anon_vma if they are the last user on release >> + */ >> + atomic_t refcount; > > Calling it just refcount is probably confusing, since > the anon_vma is also referenced by being on the chain > with others. > > Maybe "other_refcount" because it is refcounts taken > by things other than VMAs? I am sure there is a better > name possible... > external_refcount is about as good as I can think of to explain what's going on :/ -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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