Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261752AbTEQSId (ORCPT ); Sat, 17 May 2003 14:08:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261747AbTEQSId (ORCPT ); Sat, 17 May 2003 14:08:33 -0400 Received: from e32.co.us.ibm.com ([32.97.110.130]:25992 "EHLO e32.co.us.ibm.com") by vger.kernel.org with ESMTP id S261710AbTEQSIc (ORCPT ); Sat, 17 May 2003 14:08:32 -0400 Subject: Re: Race between vmtruncate and mapped areas? To: Andrea Arcangeli 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 X-Mailer: Lotus Notes Release 5.0.11 July 24, 2002 Message-ID: From: Paul McKenney Date: Sat, 17 May 2003 11:19:39 -0700 X-MIMETrack: Serialize by Router on D03NM116/03/M/IBM(Release 6.0.1 [IBM]|May 6, 2003) at 05/17/2003 12:21:08 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1498 Lines: 40 > 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. Thanx, Paul - 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/