Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261759AbTEQSaP (ORCPT ); Sat, 17 May 2003 14:30:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261757AbTEQSaP (ORCPT ); Sat, 17 May 2003 14:30:15 -0400 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:1450 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S261754AbTEQSaO (ORCPT ); Sat, 17 May 2003 14:30:14 -0400 Date: Sat, 17 May 2003 20:42:49 +0200 From: Andrea Arcangeli To: Paul McKenney Cc: Andrew Morton , dmccr@us.ibm.com, linux-kernel@vger.kernel.org, linux-kernel-owner@vger.kernel.org, linux-mm@kvack.org, mika.penttila@kolumbus.fi Subject: Re: Race between vmtruncate and mapped areas? Message-ID: <20030517184249.GV1429@dualathlon.random> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i X-GPG-Key: 1024D/68B9CB43 X-PGP-Key: 1024R/CB4660B9 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1713 Lines: 43 On Sat, May 17, 2003 at 11:19:39AM -0700, Paul McKenney wrote: > > > > > > On Thu, May 15, 2003 at 02:20:00AM -0700, Andrew Morton wrote: > > > Andrea Arcangeli wrote: > > > > > > > > and it's still racy > > > > > > damn, and it just booted ;) > > > > > > I'm just a little bit concerned over the ever-expanding inode. Do you > > > think the dual sequence numbers can be replaced by a single generation > > > counter? > > > > yes, I wrote it as a single counter first, but was unreadable and it had > > more branches, so I added the other sequence number to make it cleaner. > > I don't mind another 4 bytes, that cacheline should be hot anyways. > > > > > I do think that we should push the revalidate operation over into the > vm_ops. > > > That'll require an extra arg to ->nopage, but it has a spare one anyway > (!). > > > > not sure why you need a callback, the lowlevel if needed can serialize > > using the same locking in the address space that vmtruncate uses. I > > would wait a real case need before adding a callback. > > FYI, we verified that the revalidate callback could also do the same > job that the proposed nopagedone callback does -- permitting filesystems > that provide their on vm_operations_struct to avoid the race between > page faults and invalidating a page from a mapped file. don't you need two callbacks to avoid the race? (really I mean, to call two times a callback, the callback can be also the same) Andrea - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/