From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 17 May 2003 20:42:49 +0200 From: Andrea Arcangeli 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: Sender: owner-linux-mm@kvack.org Return-Path: 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 List-ID: 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, 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: aart@kvack.org